Multiple explosions have rocked Kano, the biggest city in northern Nigeria.
One of the blasts hit the federal police headquarters in the city and two other police stations, he says.
No-one has said they carried out the attacks, but Islamist militants have been behind a recent campaign of violence in the mainly Muslim north.
The blasts hit different neighbourhoods of the city.
Our reporter says there have been explosions at the federal police headquarters in the west of the city, one police station in the centre, and another police station in the south.
“Several explosions have occurred at the Yar Akwa police station,” an eyewitness told AFP.
“Everybody is running for his life. It’s chaotic.”
The AP news agency said one of the explosions was powerful enough to shake his car several miles away from the blast.
Our reporter says there is also a shoot-out going on at another police building in the east of the city.
Suspicion has fallen on the Islamist Boko Haram group, whose name means “Western education is forbidden”.
The group wants to establish a radical interpretation of 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.
Analysts say if Boko Haram is behind the blasts it will be one of the group’s largest simultaneous attacks, and certainly its largest assault on Kano.
It had stepped up its attacks in 2011, targeting police headquarters and the UN in the capital Abuja.
