Multiple explosions on Saturday hit Nigeria's northern city of Maiduguri, capital of Borno State, in which scores of people were feared dead, witnesses and security sources said.

A man on tricycle triggered the first explosion near a crowded market in Baga, located in the western axis of Maiduguri city at about noon, Raphael Edeh, a witness told Xinhua.

"The suspected bomber wanted to enter the fish market but was stopped and, in the process, he detonated his explosives," the witness said.

A second blast hit the Monday Market in the heart of the Maiduguri metropolis, killing more than a dozen people, said a security source.

The blast went off as rescue workers were evacuating victims of the first blast from the scene, said the source who pleaded for anonymity.

The third explosion occurred near a state-run motor park known as Borno Express at about 12:30 p.m. local time, a military officer said.

"Anti-bomb squad of the local police arrived the scene on time. Members of the squad tried to diffuse some yet-to-be exploded improvised explosive devices," the military officer, who was not authorized to speak to the media on the incident, said.

Abdul Jalo, a resident, told Xinhua the major roads leading to the area of the third explosion have been condoned off by troops.