Abdullahi Yerima, police commissioner in Adamawa state, said a suicide bomber struck at the mosque at around 01:00 p.m. and a second bomber detonated a device some 200 metresaway as worshippers fled.
Ezra Sakawa, chief medical director of Mubi general hospital, said 27 people died and 56 were injured.
Mubi has been repeatedly targeted in attacks blamed on Boko Haram since it was briefly overrun by the militants in late 2014.
Nigeria’s government and military have long maintained that the ISIS group affiliate is a spent force and on the verge of defeat. But there has been no let-up in attacks in the country’s north-east.
Boko Haram's relentless violence in the north-east of Nigeria has left at least 20,000 dead since 2009.
President Muhammadu Buhari said on March 23 that his government would grant amnesty to Boko Haram members that are ready to lay down their arms.
Rghts group Amnesty International denounced this decision and said the militant group has killed 381 civilians in Nigeria and Cameroon since the beginning of April.
