Intense fighting between the military and Islamist militants in north Nigeria is reported to have killed at least 185 civilians and destroyed 2,000 homes.
Rocket-propelled grenades and heavy gunfire bombarded the remote town of Baga near the border with Chad for hours on Friday evening, government and military officials say.
Nigeria faces a long-running insurgency in its predominantly Muslim north.
The Boko Haram insurgency has left thousands of people dead since 2009.
Residents of Baga fled into the bush and only returned on Sunday afternoon to find much of the town destroyed and human and animal corpses strewn through the streets.