At least ten people were killed after a Boko Haram suicide bomber blew himself up in the town of Djakana near the Nigerian border, a security source said on Thursday.
"Seven people were killed immediately, including the bomber. Four others later succumbed to their wounds", the security source said. "Others who were wounded are in hospital. We fear the number of victims could rise."
Most of the victims were members of a local vigilante group tasked with hunting down Boko Haram fighters.
"They were gathered in a video room when the attacker entered and triggered his explosives," the security source said.
Boko Haram's seven-year insurgency has left at least 20,000 people dead in Nigeria and neighbouring Niger, Chad and Cameroon, and made more than 2.6 million homeless.