The ancient city of Kano came under attack Friday as multiple explosions rocked the Zone 1 Headquarters of the Nigeria Police Force and three other crucial spots mainly police or security stations.
The areas are Zaria Road Police Station, Palm Centre Police Station and the State Security Service Headquarters in Kano.
The Zone 1 Police HQ is in charge of Kano, Katsina and Jigawa states.
The actual number of casualties could not be determined as at the time of filing this report, though scores of people are said to have either lost their lives or badly injured.
There was also exchange of gunfire between some policemen at the state police command and gun men also yesterday in Kano.
There is pandemonium all over the city as a result of the development.
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 police headquarters and an AP reporter says a large plume of smoke can be seen over the city.
The situation and extent of the damage is not yet clear. Islamist militants have been behind a recent campaign of violence in the mainly Muslim north.
A journalist for the AFP news agency reports hearing what sounded like about 20 explosions coming from two neighbourhoods in the city.
The Islamist Boko Haram group, whose name means "Western education is forbidden", wants to establish Sharia (Islamic law) in Nigeria and started to stage drive-by shootings in 2010 on government targets in its base in the north-eastern city of Maiduguri.
It has stepped up its attacks in 2011, attacking the headquarters of the police and the UN in the capital, Abuja.
In recent weeks, southerners, who are mostly Christians or animists, living in the north have been the targets of deadly attacks.