Boko Haram fighters have killed more than 100 people in the north Cameroon town of Fotokol, murdering residents inside their homes and a mosque, according to a local civic leader.
The attack comes a day after Chad sent troops across the border to flush the armed group out of the Nigerian town of Gamboru, which lies about offensive from Fotokol on the other side of a bridge.
The massacre also comes amid a major regional offensive against Boko Haram, which has kidnapped hundreds and killed thousands in neighbouring northern Nigeria and has mounted increasingly bloody cross-border raids.
Many of the dead were found with their throats slit, according to Cameroon's L'Oeil du Sahel newspaper.
"Boko Haram entered Fotokol through Gambaru early in the morning and they killed more than 100 people in the mosque, in the houses and they burned property," Abatchou Abatcha, the civic leader, told Reuters news agency over the telephone on Wednesday.
The fighters shot and killed one of his sons during the raid, he said.
"There are many [dead] civilians, nearly 70. The toll for the soldiers stands at six," a source in Fotokol told AFP news agency on Wednesday, adding that there were also Boko Haram bodies "everywhere".
Issa Tchiroma, Cameroon's information minister, said the Cameroon army pushed Boko Haram out of Fotokol after heavy fighting.
Main security threat
Boko Haram - whose literal translation is "Western education is forbidden" - has been fighting for five years to create an emirate governed by Islamic law.
Boko Haram is seen as the main security threat to Nigeria, Africa's biggest economy and top oil producer which holds a presidential election on February 14.
The African Union last week authorised a regional force of 7,500 troops to fight the fighters.
Chad's army and state television said it had "completely wiped out" Boko Haram bases at Gambaru and Ngala in northern Nigeria on Tuesday, killing more than 200 fighters.
Nine Chadian soldiers died, they said.
Chadian TV footage on Wednesday showed jubilant Chadian soldiers cheering near the bodies of what it said were two Boko Haram fighters.
Chad and Cameroon are deploying thousands of troops and Niger has reinforced its border against Boko Haram.
Chad, reputed to have one of the region's best militaries, has carried out air strikes on the fighters' positions over the last few days.
Former colonial power France is also sending aircraft from its base in the Chadian capital to carry out surveillance missions in the border area.