A man injured in a suicide blast is carried on a mattress by relatives at the General Hospital in northeast Nigerian town of Potiskum on January 12, 2015.

A suicide bomber, believed to be on errand for Boko Haram detonated an explosive device strapped on her body near a market in Ramirgo Village, Borno state, killing at least three people, police and civilian vigilante sources said on Saturday.

A vigilante source said four people were killed and seven injured when the explosive went off at a checkpoint, targeting the vigilantes at the entrance of the Ramirgo market.

Ishiaku Dawa, a resident who helped take victims to the hospital, said the blast damaged two patrol vehicles and that four bodies were sent to the hospital.

“Three persons including the suicide bomber died on the spot. Corpses and injured victims evacuated to General hospital,” Borno State Police Commissioner Aderemi Opadokun, who visited the scene, told Reuters in a text message.

Opadokun said the attack occurred on Saturday morning in and victims were taken to the general hospital in Askira/Uba town in Borno state about 250 km (160 miles) south of Maiduguri, the capital of Borno state and the epicentre of the insurgency.

Military spokesman Sani Kukasheka Usman confirmed the blast in a statement and said the suicide bomber had been on the way to attack the market.

Usman said the bomber was accosted by a civilian vigilante, but the bomb went off during interrogation, killing the suspect. The vigilante was injured and rushed to the hospital.

Separately, the air force said on Saturday it had conducted air strikes on Sambisa forest, one of Boko Haram’s strongholds.