Five coordinated Boko Haram bombings killed 41 people in Chad over the weekend, officials said.
Five suicide bombers, including two children and two women, hit a market and a refugee camp in Baga Sola, across Lake Chad from Nigeria, on Saturday.
"There were three explosions at the Baga Sola market and two explosions near the Dar-es-Salam refugee camp. From our information, the explosion was not in the refugee camp, but in a part of the village nearby," police spokesman Paul Manka said, according to France24.
Two suspected female suicide bombers, believed to be between 13 and 17, carried out suicide bombings in a remote district of Cameroon, killing nine people and injuring at least two dozen others.
Cameroon's Minister of Communications Issa Tchiroma Bakary confirmed the involvement of teenage girls in Sunday's bomb blasts adding that the regional jihadist group is turning kidnapped girls into suicide bombers.
"They have shifted their tactics. They have noticed it is impossible to face our forces, so they are now using young girls or young boys with explosives, who go more undetected, in areas they are told to go," said Bakary, according to Al Jazeera.
The Nigerian Army on Sunday issued a stern warning to Boko Haram militants, asking them to surrender immediately.
"This is to once again warn all Boko Haram terrorists wherever they are, to desist from all acts of terrorism, surrender themselves and face the law now," said Army spokesperson Col. Sani Usman, according to Guardian Nigeria.
"We wish to inform them that we are aware of all their hideouts, camps and enclaves. They should follow their colleagues who have so far surrendered. Failure to surrender will result in serious consequences as the troops are fast closing up on them," he said.