Air force spokesman Air Vice Marshal Ibikunle Daramola said that all those on board the small aircraft had died.
Witnesses say they heard a loud sound, then the aircraft burst into flames, reports the BBC’s Ishaq Khalid.
A witness told Reuters the smell of burning and chemicals lingered in the air at the site of the crash, in scrubland just outside the airport perimeter.
Vice Marshal Daramola told the BBC that the aircraft was on a mission to try to rescue 42 people, including students and staff abducted from their boarding school in the town of Kagara on Wednesday, when it turned back following engine failure.
At least 43 people have been killed in what the Nigerian president has described as an “insane” attack in north-east Nigeria on Saturday.
The attackers tied up agricultural labourers working in rice fields and slit their throats near Maiduguri, the capital of Borno state, reports say.
This is one of the worst attacks in recent months in a region where the Boko Haram and the Islamic State West Africa insurgent groups are active.
No-one has yet claimed responsibility.
“I condemn the killing of our hard-working farmers by terrorists in Borno state. The entire country is hurt by these senseless killings. My thoughts are with their families in this time of grief. May their souls rest in peace,” said President Muhammadu Buhari.
President Buhari also described “the terrorist killings as insane”, according to his spokesman Garba Shehu.
“We have recovered 43 dead bodies, all of them slaughtered, along with six others with serious injuries,” a local militiaman who helped the survivors told the AFP news agency.
Some farm workers are still missing, with one resident and Amnesty International saying 10 women were among them.
The victims were labourers from Sokoto state in north-western Nigeria, roughly 1,000 km (600 miles) away, who had travelled to the north-east to find work, another militiaman told AFP.
The governor of Borno state, Babagana Zulum, attended the victims’ funerals on Sunday.
“It is disheartening that more than 40 citizens were slaughtered while they were working in their farmlands,” he told journalists.
“Our people are in very difficult situations, they are in two different extreme conditions: in one side, [if] they stay at home, they may be killed by hunger and starvation; on the other, they go out to their farmlands and risk getting killed by the insurgents. This is very sad.”
He called on the federal government to recruit more soldiers and members of other security forces to protect farmers in the region.
The farmers “were attacked because they had on Friday disarmed and arrested a Boko Haram gunman who had been tormenting them”, a member of the local parliament, Ahmed Satomi, told newspaper Premium Times.
Correspondents say farmers have previously been attacked by militants of the Islamist group Boko Haram, who suspect them of passing on information to the military.
Last month, Boko Haram fighters killed 22 farmers working on irrigation fields in two separate incidents.
On Sunday, six soldiers were reportedly killed in a jihadist ambush near the town of Baga in Borno State, says the BBC’s Chris Ewokor, in Abuja.
The soldiers were on their way to the area to boost security at a food distribution depot for people displaced by the conflict.
Despite regional efforts to end Boko Haram’s campaign of violence, the group has stepped up its attacks in recent months.
The Nigerian government has repeatedly claimed that the Islamist militant groups have been technically defeated, correspondents say.
President Buhari, who five years ago asserted that Boko Haram had been defeated, said he had given all the support needed to the armed forces to protect Nigeria’s population.
But the Nigerian military has been unable to quell the insurgency affecting the region, in which tens of thousands have been killed or abducted.
The Nigerian army has rejected claims it killed unarmed protesters at a rally in Lagos in October, saying its soldiers were firing blank bullets.
Brigadier General Ahmed Taiwo presented video evidence to back up his claims made to a panel of inquiry.
Amnesty International says 12 people were killed when soldiers opened fire on a protest about police brutality in the wealthy Lagos suburb of Lekki.
Multiple eyewitnesses have told the BBC they saw soldiers shoot people.
Some 1,000 protesters had gathered at the Lekki toll gate on 20 October to prevent cars using a major motorway. Soldiers were reportedly seen barricading the protest site moments before the shooting started.
Brig Gen Taiwo told the judicial panel investigating alleged historic abuses by Sars there had been “a lot of misinformation” about his troops. Their “only crime was to report for duty to protect us all”.
He pointed to video showing what appeared to be soldiers at the scene. “You can see they are firing in the air, and firing blank ammunitions.”
Responding to a claim that a witness had seen a dead body at the scene, he said “the casualty she saw had been overcome by shock”, AFP news agency reports.
It is not clear if he will respond to the many other accounts from eyewitnesses.
Since the shooting those involved in the protests say they are being targeted by the government, the BBC’s Mayeni Jones reports.
A number of protesters and companies say their bank accounts have been frozen and others have been arrested. The passport of a lawyer who organised legal aid for the protesters was seized as she tried to leave the country, although it has now been returned to her.
Nationwide protests erupted on 8 October calling for an end to the Special Anti-Robbery Squad, which had been accused of widespread human rights violations, including illegal detention, torture and extrajudicial killings.
President Muhammadu Buhari disbanded the squad a few days later, but the protests continued with demands for more changes in the security forces and reforms to the way the country is run.
Following the 20 October attack, Amnesty International Nigeria said it had evidence from hospital records and witnesses to show that “the Nigerian military opened fire on thousands of people who were peacefully calling for good governance and an end to police brutality”.
The Lagos state government said 30 people had been injured with one fatality.
Lagos and other parts of Nigeria have seen buildings torched, shopping centres looted and prisons attacked since the shooting.
Nigeria’s vice-president has promised justice for victims shot during the protests amid widespread condemnation from international leaders.
The Chairman of the Foreign Affairs Committee of Parliament, Frank Annoh-Dompreh, has urged the President of Nigeria, Muhammadu Buhari, to show a willingness to dialogue with protestors to bring an end to protests and violence in Nigeria.
Speaking on The Point of View, the Foreign Affairs Committee Chair for Parliament stated that the willingness of President Buhari to sit down with the protestors to dialogue will allow the other parties involved to open up about what they want and this will be a good start to solving the matter.
“Japheth was clearly lamenting the silence coming from the government, so we will urge president Buhari to open up and show a willingness to dialogue and to mediate. I think if he does that, the other interested parties will open up, and then once they begin to sit behind the table and talk, that will calm protestors down and that will be a very good beginning for a resolution of the matter.”
“I dare say that, unless our good brothers in Nigeria themselves show that will, it becomes very difficult. All the world leaders can come out with the praise and the commentary but the Nigerian government must bite the bullet by showing a will to sit, talk and mediate, then the other leaders will only come in to complement what the Nigerian leaders will do,” he added.
Many young people across Nigeria have since Friday, October 9, been protesting against police brutality and demand widespread reforms to the security apparatus.
Mr. Annoh-Dompreh stated that a lot more is expected of Ghana in relation to the #EndSARS protests because of President Akufo-Addo’s position in ECOWAS and the relationship between the countries.
He added that Ghana cannot afford to be silent because instability in Nigeria could have an effect not only in Ghana but the sub-regions and the world in the long run.
The Foreign Affairs committee chair stated that on the legislative front, because of the friendship between the Ghanaian Speaker of Parliament and the Speaker of Nigeria he is sure that a deal will so be in play.
“I think that there is a legislative diplomacy approach and today our Speaker will be called upon by the Nigerian High Commission. I know there is a wonderful friendship between them, so we are hoping that will be a good process towards this.”
Police say he also confessed to the murders of six other women elsewhere but he was not charged for those murders for lack of evidence.
Authorities say the pattern of the murders point to a serial killing – he had sex with his victims before binding their arms and feet with strips of white sheets.
He also used sheets to strangle them, the court heard.
Several of his victims were sex workers.
How was he caught?
At the beginning of the case and unrepresented by a counsel, David-West had pleaded guilty to the murders but the judge demanded a trial because of the “gravity of the crime”.
At the time, authorities had suspected that he was working with accomplices but could not find any evidence as the case went to trial.https://emp.bbc.com/emp/SMPj/2.35.13/iframe.htmlmedia captionAt least eight women have been killed in Port Harcourt, apparently by the same person.
At the height of the killings in September last year, outraged citizens of Port Harcourt took to the streets, calling on authorities to solve the murders.
He was arrested on 19 September while trying to leave Port Harcourt as investigators closed in on him.
CCTV had captured him leaving a hotel and the circulated photo went viral on social media.
Security agents found him in a commercial bus travelling to Uyo in Akwa Ibom state, 45 minutes away from Port Harcourt.
What do we know about the killer?
David-West was born in the fishing town of Buguma in Rivers state, an oil-producing coastal community known for its beaches.
The town has a history with oil militants who operated out of its numerous mangrove swamps at the height of the oil militancy in Nigeria’s Niger Delta in the early 2000s.
Police say David-West was a member of the Greenlanders – also known as Dey Gbam, a mafia-styled street gang that sprung out of the armed militant groups.
Those who know him told the BBC that he was an only child born into a polygamous home, but he and his mother lived separately from the rest of the family.
Reporters who saw him in court describe a man whose behaviour was erratic.
“He was quick-tempered, always interjected the judge, and tried to defend himself despite having a lawyer,” said journalist Alwell Ene.
He used low-cost hotels, with poor security and without CCTV cameras, in the city centre and on the fringes of Port Harcourt, according to the police.
On one occasion he murdered a sex worker in a brothel in the Rumuola area of Port Harcourt, a known red-light zone in the city.
Who are the victims?
Very little is known about the victims, except for the names of the nine:
Kelechi Bridget Onuoha
The BBC’s Karina Igonikon in Port Harcourt says friends and family members of the deceased never appeared in court, except for the dad of one of the victims who only came on the opening day of the trial.
“It was as if they had no-one, no address, nothing to trace them with,” she said.
Police say he also confessed to killing six other women in Abia, Imo, Edo, Lagos and Edo states but he was not charged for those murders.
“No-one came forward for those murders and there was little evidence to pin them on him,” state prosecutor Chidi Ekeh told the BBC.
There are disputes about the identity of the women, and how they were able to follow the killer to the hotel.
Investigators say he lured his victims by claiming to be a military officer and promising huge amounts of money for their time.
One of the victims, Jennifer Nwokocha, was said to have arrived Port Harcourt from Lagos to celebrate her birthday.
“They met at the hotel where she was staying and had drinks, exchanged numbers and met up later in the night where she met her death,” an investigator told the BBC.
Police say he threatened the women with a knife and prevented them from raising alarm.
Before killing them he robbed them of money, ATM cards and other valuables.
“We found the victims naked, bound with a white strip of cloth on their ankles and arms and neck.
“Although there is no concrete evidence that points to some form of ritualistic killing, I personally believe it was connected to such,” Mr Ekeh told the BBC.
The one who survived
Benita Etim, a 23-year-old sex-worker, survived a night with the killer.
She was not a witness during the trial as authorities say her whereabouts are unknown despite being told not to leave the state.
In an interview with the BBC in September last year, she narrated how a man she met on 18 August had tied her up in a hotel room.
She described how she was raped before he threatened her with a knife and tied her up to a chair.
“He cut the bed sheet into strings and bound my hands and legs to the chair and used another strip to tie my mouth.
“I shouted but nobody heard me because he had turned on the volume of the TV and the power generating set was close to the room,” she said.
“I begged him not to kill me.”
At this point, he left the room with her phone and never returned.
Hotel staff found her the next day after she had somehow managed to force the gag out of her mouth and screamed for help.