At least 17 people were killed on Tuesday when an explosion ripped through a busy market in a mostly Muslim city in northeast Nigeria on a public holiday marking the holy birth of the Prophet Mohammad (sws).

At least 17 people were killed on Tuesday when an explosion ripped through a busy market in a mostly Muslim city in northeast Nigeria on a public holiday marking the holy birth of the Prophet Mohammad (sws).

"From our preliminary reports, we have 17 dead and at least five injured from the blast in the post office area" in Maiduguri, the police chief for Borno state, Lawan Tanko, said.

Tanko warned that toll could rise as casualties were taken from the bustling market to medical centers for treatment.

Initial reports suggested the blast was caused by a car bomb or a suicide bomber but there was no immediate confirmation from the authorities.

"The bomb was detonated in the midst of a large crowd of traders while a truck carrying firewood was passing by," said Tanko.

The explosion happened at about 1:30 pm (1230 GMT) in a part of the city hit previously by militants from the outlawed extremist group Boko Haram.

A police officer, who asked not be identified because he was not authorized to speak to the media, said the impact of the blast could be felt three kilometers (nearly two miles) away.