At least 41 people have died in a suicide car bomb that struck a bus station in the city of Kano, northern Nigeria's busiest commercial center, in the most deadly attack in nine months that is blamed on Boko Haram rebels, officials say.

The blasts on Monday destroyed several buses filled with passengers who were waiting to leave the station in Sabon Gari, an area mostly inhabited by immigrants from Nigeria's largely Christian south, according to Reuters news agency.

Al Jazeera's Ahmed Idris, reporting from Nigeria, said a car laden with explosives rammed into buses and detonated.

"The area has been surrounded by security forces and evacuations and investigations continue," he said.

Meanwhile Al Jazeera's West Africa correspondent Yvonne Ndege, reporting from Abuja, said neither the emergency or security services have confirmed details of the blasts or the death toll.

"There was a huge blast at the New Road motor park," said area mechanic Tunde Kazeem. "The blast was followed by billows of black smoke and there was a lot of confusion with people rushing out of the motor park, some of them with blood on their clothes."

Kano, in the country's mostly Muslim north, is among the cities attacked repeatedly by the Boko Haram, a group blamed for killing hundreds in Nigeria since 2009.

"I saw three buses on fire. One of them was fully loaded with passengers waiting to leave the station at the time of the blasts," a rescue official who requested anonymity told AFP news agency.

The station was attacked in January of last year in a blast which wounded several people and was blamed on Boko Haram.

"I ran for my dear life and managed to get out of the park after the second blast. Many people are lying dead. See, my

clothes are covered in blood," said Ibrahim Bello, holding up a blood-soaked shirt.

No group has claimed responsibility for Monday's attack so far.

The National Emergency Management Authority said: "Rescuers and security personnel are yet to determine the source of explosions that occured this evening at a motor park," in a statement. "While casualty figures are not available at the moment, the seriously injured have been taken to hospital and bodies evacuated."