Nigerian Boko Haram fighters have gone on a rampage in the Cameroonian border town of Fotokol, massacring civilians and torching a mosque before being repelled by regional forces.
The onslaught came a day after Chad sent troops across the border to flush the jihadists out of the Nigerian town of Gamboru.
Chad's army said it had killed more than 200 Boko Haram militants in the intervention - the first by regional forces against Boko Haram on its home ground.
But some of the insurgents escaped and slipped back across the border into Fotokol at dawn to make a fresh stand.
"Boko Haram inflicted so much damage here this morning. They have killed dozens of people," Umar Babakalli, a resident of Fotokol, told AFP by telephone on Wednesday.
Several residents said civilians' throats were slit and that the town's main mosque was torched.
"They burnt houses and killed civilians as well as soldiers," a source close to security forces said.
Another resident who had fled to another town told AFP he knew of at least 10 people who had been killed.
After several hours of clashes Cameroonian troops, backed by Chadian forces who scrambled back from Nigeria to help guard the town, managed to repel the assault.
"People are coming back little by little to assess the damage. The survivors among the attackers have left the town," a source close to the Cameroonian security services said.
No official death toll was immediately available.
On Tuesday, nine Chadian soldiers were killed and 21 were injured in Gamboru after around 2000 troops backed by armoured vehicles poured across the border to take the fight to Boko Haram after days of clashes.
The sound of automatic gunfire could still be heard Wednesday in the town as the troops combed the town for remaining rebel elements.
