Gunmen killed dozens at a school in the northeast Nigerian town of Mamudo on Saturday. Believed to be members of the Islamist Boko Haram movement, the attackers herded students and staff into a dormitory before throwing explosives inside and firing into the building.

A medical worker and local residents claim that 42 were killed, though the Nigerian military claims the death toll was roughly half that.

Haliru Aliyu of the Potiskum General Hospital, where many of the victims were treated, said, “we received 42 dead bodies of students and other staff of Government Secondary School (in) Mamudo last night. Some of them had gunshot wounds.” Hospital personnel are currently combing the area in search of students who might have fled the scene and are hiding.

“So far six students have been found and are now in the hospital being treated for gunshot wounds,” Aliyu said.

Mamudo is roughly three miles from Potiskum. Located in the state of Yobe, Potiskum is a commercial center for the area and has been a flashpoint in the Boko Haram insurgency in recent months. This most recent attack is thought to be a reprisal for the killing of 22 Boko Haram fighters by the state military on Thursday.

“It was a gory sight. People who went to the hospital and saw the bodies shed tears,” claimed a local resident who did not want to be identified. “There were 42 bodies, most of them were students. Some of them had parts of their bodies blown off and badly burnt while others had gunshot wounds.”

Boko Haram (which, in the Hausa language, means “Western education is sinful”) is a jihadist group located in Nigeria, Cameroon, and Niger. Founded in 2001, the organization seeks to establish sharia law in its home area. Some analysts have linked the group to Al-Qaeda in the Islamic Maghreb (AQIM), though Boko Haram’s general lack of organizational structure makes any sort of formal relationship unlikely.