Nigerian soldiers have shot dead dozens of young men during raids in a city seen as a stronghold of Boko Haram, an armed Islamist group, residents have told reporters.
The reported military operations targeted four neighbourhoods of Maiduguri on Friday. Residents said the troops conducting the raids ordered males in their teens and twenties to separate from the others in the area.
In the Kalari neighbourhood, soldiers told the young men "to lie face down on the ground", then asked the rest to look away, according to witnesses.
"All we heard were gunshots. They shot them on the spot," said the elderly religious leader, who did not want to be named.
"They did the same in three other neighbourhoods. We went to the morgue to collect the bodies and we found 48 in all."
A resident of the city's Gwange area told the AFP news agency that the alleged massacre was "like a movie scene".
The troops "picked young men from their homes and were shooting them dead before everyone and took the bodies away to the hospital. I have never seen something like this", he said, also requesting that his name be withheld.
The Sabon Lamba and Gomboru neighbourhoods were also said to have been raided.
A morgue attendant at the Maiduguri General Hospital said they "received 39 bodies yesterday which were brought in by soldiers. They all have fresh gunshot wounds".
A military source declined to comment on the allegations, saying only that if such killings had taken place they were "unjustified".
Amnesty International has charged Nigeria's security forces with committing rights violations, including summary executions, in the campaign to crush Boko Haram. Nigeria has rejected the allegations.
In a report released on Thursday, the rights group documented a series of alleged extra-judicial killings by the military and police in Maiduguri, saying such conduct had fuelled further attacks and deepened a cycle of violence.
At around midday on Friday in Maiduguri, gunmen disguised as visitors entered the home of a prominent former general, Mohammed Shuwa, killing him and one of his guests, a military statement said.
Shuwa, 79, was a key leader in Nigeria's 1967-1970 Biafran civil war and served under several of the country's military leaders.
In an interview at his home in May, Shuwa showed AFP the gun he carried for protection and said he could be targeted by Boko Haram.
The military blamed Boko Haram for the killings, and the attack on Shuwa resembled those previously claimed by the group, who have often targeted notable government and military figures.
The Islamists have also attacked Christians in churches and various symbols of authority as part of an armed campaign that is estimated to have left 2,800 dead since 2009, including killings by the security services.
Boko Haram has said it wants to create an Islamic state in the north, but its demands have varied widely and some analysts believe the group is now made up of various different cells.