Nigeria's Kano rocked by explosions

A series of about 20 explosions has rocked Kano, the main city in the north of Nigeria.

The BBC's Yusuf Yakasai in the city says there is pandemonium with people running all over the place.
One of the blasts is believed to be at the headquarters of the city's police, he says.
The situation and extent of the damage is not yet clear. Islamist militants have been behind a recent campaign of violence in the north.