Heavy casualties are feared following two loud explosions near a crowded market in the volatile central Nigerian city of Jos.
The BBC’s Ishaq Khalid, in neighbouring Bauchi, says the market was very crowded at the time.
The cause of the blasts has not been confirmed. Jos has seen several deadly clashes between Christian and Muslim groups in recent years.
Islamist group Boko Haram has also previously targeted the area.
A suicide attack in the northern city of Kano on Monday killed four people.
A regional official confirmed there had been two blasts in Jos, the capital of Plateau state, but told Agence France-Presse news agency that he did not have any casualty figures yet.
A military spokesman told AFP one bomb had been placed in a truck and another in a minibus, but this has not been independently confirmed.
Plateau state lies on the fault-line which divides Nigeria’s largely Muslim north from its mainly Christian south.
The state has been dogged by violence blamed on land disputes between semi-nomadic Muslim Fulani herdsmen and mainly Christian Berom farmers.
The Nigerian government is also currently trying to trace more than 200 girls captured by Boko Haram in April from a boarding school in the north-eastern town of Chibok.
The case has shocked the world and prompted foreign powers to send military advisers to assist Nigeria’s army tackle the insurgency.
On Tuesday, parliament approved a six-month extension of a state of emergency in three north-eastern states – Adamawa, Borno and Yobe.
More than 1,000 people have been killed in Boko Haram attacks this year but the government says it has pushed the militants back into their strongholds in Borno.