Two female suicide bombers attacked a mosque in a town near Cameroon’s border with Nigeria during morning prayers on Wednesday, killing at least 12 people and wounding about a dozen others, the governor of the region said.

The attack in the town of Kolofata is believed to have been carried out by Boko Haram members who crossed the border into Cameroon a few days ago, said Midjiyawa Bakari. The town of Kolofata in Cameroon’s far north near the border has been repeatedly attacked by Boko Haram, a Nigerian Islamic extremist group. Boko Haram has pledged allegiance to ISIS

“Eleven worshippers were killed at the scene. A twelfth died of their wounds in hospital,” the security source said.

Another source close to the security services The bombing came after two people were killed overnight in the same area in another attack blamed on Boko Haram.

Cameroon has beefed up its military presence along the Nigerian border as part of a regional coalition, after years of doing little to stop Boko Haram fighters using its territory as a rear base to arm and equip themselves.

Over the past year, Boko Haram has stepped up cross-border attacks in Niger, Chad and Cameroon while also continuing to mount shooting and suicide assaults on markets, mosques and other mostly civilian targets within Nigeria itself.