The blasts in Jos happened at a makeshift market near the Terminus bus station, which had been set up after a twin car bomb attack in May that left at least 118 people dead.
Mohammed Abdulsalam, coordinator for the National Emergency Management Agency (NEMA) in the city, said the scene of the attack was a densely populated area.
“The bodies recovered so far are 31 but rescue workers are at the scene and the figures may change,” added Pam Ayuba, spokesman for the Plateau state governor Jonah Jang.
The city, which is the capital of Plateau, lies in Nigeria’s “Middle Belt” where the mainly Muslim north meets the mostly Christian south.
It has been targeted by Boko Haram Islamists in the past but is also a hotbed of ethnic and sectarian tensions that frequently boil over into deadly violence.