Four suicide bomb attacks hit the city of Maiduguri killing at least 54 people and wounding 143 in the heartland of Nigeria's northeastern Islamic uprising, police said. The blasts occurred over four hours in locations from a busy fish market to a crowded bus station, said Police Commissioner Clement Adoda. A fifth explosion from a car bomb at a military checkpoint 75 kilometers outside the city wounded a soldier and two members of a civilian self-defence unit. The bomber apparently wanted to reach Maiduguri, said a police officer at the scene. In the deadliest blast, 18 people died when a suicide bomber blew himself up in a tricycle taxi at the entrance to the bustling Baga fish market, police said. "I saw many dead bodies lying on the ground, many dead, and several others badly injured," said fish seller Idi Idrisa. About an hour later a second explosion rocked the post office shopping area near the market, according to witness Baban Musa, who said there were many casualties. A third blast was detonated at Monday Market, the biggest in Maiduguri, and a fourth explosion ripped through the Borno Express bus station. No one immediately claimed responsibility for the attacks but they bear the hallmarks of the Boko Haram Islamic extremist group. Maiduguri is the birthplace of Boko Haram and the extremists have tried to seize the city with armed assaults by hundreds of fighters and have made it the target for many bombings since they were driven from their base there after a military state of emergency was declared in May 2013. Boko Haram has increased suicide bombings and village attacks in recent weeks as forces from Nigeria and Chad have driven the insurgents from a score of towns along Nigeria's border with Cameroon. The insurgents also have attacked villages in Cameroon and Niger in response to Nigeria's neighbours forming a multinational force to confront the spreading Islamic uprising.