Soldiers in northeast Nigeria shot dead more than 40 people, likely civilians, during an operation in a city long under attack by a radical Islamist sect, a hospital official said Friday.

An official at Maiduguri General Hospital said soldiers brought the corpses, mostly young men, into the hospital Thursday night. The official said Friday that the dead came from the Kalari neighborhood and did not appear to be armed combatants of the Islamist sect known as Boko Haram.

The official spoke on condition of anonymity out of fear of angering the soldiers.

Lt. Col. Sagir Musa declined to discuss the killings Friday. However, the Hausa language service of the BBC reported its journalists spoke to residents in the city who said the youths had been rounded up in house-to-house searches by soldiers and later were shot dead in a field.

Both Amnesty International and Human Rights Watch have said Nigerian security, as well as Boko Haram, have probably committed crimes against humanity in their fighting. In October, soldiers shot dead more than 30 civilians and burned homes in Maiduguri after a bomb suspected to have been planted by the sect killed a lieutenant.

In a separate incident in Maiduguri, a retired general was shot dead by gunmen suspected to be the Islamist extremists. The killing of Gen. Mamman Shuwa may spark more retaliatory attacks in this city by Nigerian security forces, who already face growing international criticism for abusing and detaining civilians in its ongoing fight against the Islamist extremist sect. The general's murder also raises questions about whether an alleged Boko Haram member's offer of peace talks could be genuine, as it remains unclear whether any one person actually controls the sect's many cells.

Gunmen raided the home of Shuwa on Friday, a general who served in Nigeria's military during its 1960s civil war. The gunmen killed Shuwa and a guest in the attack, Musa said.

"The terrorists that carried out the killing of the late general will be brought to book," the lieutenant colonel said.

Boko Haram, whose name means "Western education is sacrilege" in the Hausa language of Nigeria's Muslim north, has been attacking government buildings and security forces heavily over the last year and a half. This year alone, the sect is blamed for killing more than 720 people, according to an Associated Press count.

The latest killings raise new concerns over a supposed offer for peace negotiations by an alleged member of the sect. On Thursday, a man who identified himself as Abu Mohammed Ibn Abdulaziz said the peace talks were possible if Nigeria met certain preconditions, like holding them in Saudi Arabia and involving former military ruler Muhammadu Buhari. The man said those were conditions set by Abubakar Shekau, Boko Haram's leader.

The call came through the channels that Boko Haram usually communicates with journalists, who gathered at the local office of the Nigeria Union of Journalists to listen. However, Abdulaziz spoke entirely in English, which is unusual for the sect. Also, journalists ordinarily hear from a spokesman who uses the nom de guerre Abul Qaqa in such calls. The man also did not call for the implementation of Shariah law across Nigeria, a multiethnic nation of more than 160 million people. That long has been a demand of the sect.

Rumors about indirect peace talks between Nigeria's government and the sect have floated around for some time, however the sect has denied negotiating with the government.