Four people were killed late on Saturday when suicide bombers attacked a village on the outskirts of Maiduguri city in northeastern Nigeria, police said.

Borno state police spokesman Victor Isuku said the incident occurred when three bombers — a man and two women — tried to enter Umarari village just outside Maiduguri.

“They detonated the IEDs (improvised explosive devices) strapped to their bodies while running to different directions,” Isuku said.

Among the dead was a local vigilante and a woman and her two children, he said. Another eight people were wounded.

Ibrahim Abdulkadir, spokesman for the National Emergency Management Agency (NEMA), said the vigilante had tried to prevent the bombers from entering the village.

“The vigilante was trying to stop them and that was when he was engulfed by the bomb and the woman was nearby,” Abdulkadir explained.

The three bombers also died in the blasts, he said.

It is the latest in a string of attacks in the last few days to bear the hallmarks of Boko Haram, which has killed around 15,000 people and forced more than 2 million people to flee their homes in Africa’s most populous nation since 2009.

Boko Haram’s elusive leader Abubakar Shekau made his first appearance in months last week, claiming responsibility for a spate of suicide bombings. He also denied that 5,000 hostages held by the group had been freed.

The violence has triggered a dire humanitarian crisis in northeast Nigeria and the wider Lake Chad region, which has also been hit by the conflict.

Nigerian troops, with the help of regional forces from Cameroon, Chad and Niger, as well as Benin, have since early 2015 managed to claw back most of the territory lost to Boko Haram in 2014.

But despite claims from the Nigerian military that the group is on the verge of defeat, suicide bomb attacks remain a threat to civilians, particularly in Maiduguri.

It also carries out cross-border attacks in neighboring Cameroon, Chad and Niger.