KANO (Reuters) - At least two separate explosions shook the police headquarters and passport office in Nigeria's second biggest city of Kano on Friday, sources who witnessed the blasts told Reuters.
A Reuters witness at the scene of the police headquarters blast saw smoke billowing out of the building, windows blown out and the roof collapsed. Firefighters had sprayed the roof with a hose to try to douse the flames.
It was not yet clear if there had been any casualties.
Witnesses said the bomber pulled up to the building on a motorbike then got off and ran at it holding a bag.
"We tried to stop him but he ran in forcefully with his bag. All of a sudden there was a blast. You can see for yourself the building is damaged," said a policeman at scene.
Police said a second blast had hit Kano's passport office.
Kano, like other northern cities, has been plagued by an insurgency led by Islamist sect Boko Haram, blamed for scores of bombings and shootings against mostly government targets that are growing in scale and sophistication.
A bomb attack on a Catholic church just outside the capital Abuja on Christmas Day claimed by the group killed 37 people and wounded 57.
Last August, a suicide bomber blew up the U.N. Nigeria headquarters in Abuja, killing at 24 people.
(Reporting by Mike Oboh; Writing by Tim Cocks; Editing by Louise Ireland)