A morning bomb blast near a market in the Nigerian city of Maiduguri caused havoc Tuesday, with fears that dozens of people may have been killed, according to defense officials.
It was the latest in a series of terror attacks in the country's troubled north.
Nigeria's Defense Ministry reported the explosion on its Twitter feed, saying a vehicle loaded with charcoal and explosives blew up at the market. It said the area had been cordoned off, but gave no casualty figures.
There was no immediate claim of responsibility for the attack, however suspicion fell on the violent Islamist group Boko Haram or a similar militia. Maiduguri is the birthplace and traditional stronghold of Boko Haram.
There were reports that about 18 people had been killed, but witnesses said they saw dozens of bodies, the Associated Press reported.
The explosion occurred at around 8:20 a.m., when the market is crowded, the Premium Times, the local newspaper, reported. The driver of the explosives-laden vehicle was reportedly killed in the blast.
The bombing followed an attack Friday on a hotel in the northern Bauchi state, where people had gathered to watch a World Cup game on TV. Eleven people were killed in that blast.
Dozens more died in attacks on villages in northeastern Nigeria over the weekend. In one of the incidents, gunmen opened fire on church-goers, killing dozens of people.
Boko Haram has stepped up its attacks in recent months, targeting schools, hotels, markets, bus stations and villages. Nigerian security forces have seemed unable to contain the violence.
In April, Boko Haram kidnapped hundreds of schoolgirls from the northern village of Chibok, 219 of whom remain in captivity. The Nigerian government on Monday announced the arrest of a suspect in the case.
Defense Ministry spokesman Chris Olukolade told journalists that the suspect, identified as Babuji Yaari, was a Chibok businessman who was involved in a vigilante group set up to defend the village from Boko Haram.
Olukolade alleged that Yaari used his position in the group to cover up his affiliation with Boko Haram and to glean intelligence. Yaari is also suspected to have been involved in the assassination of a northern religious figure, the Emir of Gwoza, who was killed in May when his convoy was attacked, Olukolade said.
Nigerian authorities said that after questioning Yaari, they arrested two women. One is accused of being a spy who procured arms for Boko Haram, and the other was allegedly the group's "pay master."