Four teenage suicide bombers killed two people and injured 16 others in a residential area in the northeast Nigerian city of Maiduguri, a disaster agency spokesman said on Wednesday.
The girls knocked on the door of a house and then detonated their devices, a representative of the state-run emergency service in Borno State said.
The focus on individual homes is a new tactic.
The blasts in the Muna Garage area, on the edge of the city worst hit by jihadist group Boko Haram's eight year insurgency, occurred around 1:15 a.m (0015 GMT), National Emergency Management Agency (NEMA) spokesman Abdulkadir Ibrahim said.
"Four female teenage suicide bombers and two other men died," he said.