At least 60 people are reported dead after gunmen set off explosives and fired on a cattle market in northeastern Nigeria overnight.
It is not yet clear who was behind the attack on Wednesday night in the town of Potiskum, in Yobe state.
The town has been an occasional target for militant Islamist sect Boko Haram.
Boko Haram has been fighting a low-level insurgency for more than two years.
It usually targets police or authority figures, and although civilians have increasingly borne the brunt of its attacks, they are normally targeted for being a perceived enemy of the group, such as Christians, rather than being randomly killed.
Violence in Nigeria, especially in parts of the north or the volatile Middle Belt, is sometimes driven by ethnic rivalry over land and resources that has little to do with the Boko Haram attacks.
