"It was a remote-controlled landmine that I think was put there last night. Since we patrol the streets in the daytime, it could not have been buried in the day," he said.

Witnesses said they saw the vehicle along with two other police vans patrolling the streets of Mogadishu .

"The car has been surrounded by policemen and Somali government officers. I can hear gun shots. I don't know who the troops are shooting at," a local reporter, who declined to be named, told Reuters from his office rooftop close to the scene.

There has been relative calm in the coastal city since the interim government, supported by Ethiopia and the United States, declared victory over Islamic courts fighters more than a week ago.