Pakistani policemen inspect a damaged police station following a suicide car blast in the northwestern town of Kohat. Militants have unleashed coordinated attacks on Pakistani police in which 27 people died, storming offices in Lahore and bombing a northwest station to escalate 11 days of carnage.(Xinhua/AFP)

Witnesses said that the gunmen and security forces exchanged fire for some time.

Deputy Inspector General Police Shoaib Dastageer said that six policemen were killed and several injured in the police training center attack. He said that four attackers were also killed in the fighting.

Meanwhile, another group of around 10 gunmen, wearing police uniform, entered another elite police center at Bedian area in Lahore and opened gunfire after throwing hand grenades.

Police said hostages taken by the attackers have been secured, and the security forces are conducting clearance operation. During the operation, five militants were killed and six policemen were also killed.

Eyewitnesses said nine to ten militants including three women were involved in the attack.

Security forces helicopters conducted aerial surveillance in the area to pinpoint the location of terrorists. Troops and paramilitary force Rangers were also called in support of the police and they surrounded the building, police said.

Meanwhile, 11 persons have been taken out from the building in injured condition.

Ambulances rushed to the site and shifted the injured to the nearby Ganga Ram Hospital.

In the capital of Islamabad, all police offices were vacated due to threats, Police Chief Kalim Imam said.

Pakistani Interior Minister Rehman Malik said that all the four provinces are in red alert and the security forces are keeping on high alert,

A full-fledged operation will be started shortly as the Rangershave been deployed across Lahore, the minister said.