A Nigerian civil defense official says a bomb blast near a market in the northeast Nigerian city of Yola has killed 31 people.

Sa'ad Bello of the National Emergency Management Agency said Friday another 38 people are being treated in the hospitals.

There was no immediate claim of responsibility but Thursday evening's explosion as merchants were closing shop and others were hurrying to make last-minute purchases bore all the marks of the extremist Boko Haram movement.

The group has stepped up attacks in recent weeks after a months-long lull while a multinational force drove it from the towns where it had declared an Islamic caliphate.

More than 60 people have been killed in attacks since the weekend in Maiduguri, the northeastern city that is the birthplace of Boko Haram.