Three women suicide bombers blew themselves up at the entrance to a camp for displaced people in northeast Nigeria on Tuesday, killing 28 people and wounding 82, in an attack bearing the hallmark of Boko Haram militants, local sources said.

The attack — the latest in a string of assaults in the troubled region — took place in the town of Mandarari, 25 kilometers from Maiduguri, the capital of Borno state, said Baba Kura, a member of a vigilante force set up to fight militants.

“Three female bombers triggered their explosive outside of the IDP (internally displaced persons) camp… killing 28 people and wounding 82 others,” Kura said.

The first assailant blew herself up, triggering panic, Kura said.

“People were trying to close their shops when two other female bombers triggered their explosives, causing most of the casualties,” he said.

Ibrahim Liman, the head of a local anti-militant militia force, confirmed the details of the attack, and said that more than 80 injured had been taken to Maiduguri hospital.

A source at the hospital said a “huge number” of patients had arrived.

Northeast Nigeria is a hotbed of activity by Boko Haram, involving shootings, bombings and kidnappings.