A car laden with explosives rammed a building where police interrogate high-value suspects, in Lahore on Monday, killing at least 12 people and leaving 61 injured, 29 of them critically. (See First Pics)

A bomb disposal squad said about 800 kg of explosives was used to attack the Federal Investigative Agency building, causing a 17-foot crater as an impact of the blast.
 
The building has been damaged and there could be more casualties as more people are believed to be trapped under the rubble. Heavy lifting machinery is helping lift debris at the site.

Pakistani media reports said the injured had been moved to Jinnah Hospital and Sheikh Zayed Hospital in Lahore. Injuries sustained in the blast were serious.

Lahore city has been put on high alert.

Police official Chaudhry Shafiq said it appeared a suicide bomber rammed his explosives-laden car into the perimeter wall.

A schoolgirl is among those dead. Hospital official Jawed Akram said the dead included a woman and a young girl.

"People are coming with multiple wounds, many with head injuries and broken limbs," he said.

Parts of the brick building appeared to have collapsed, and there were piles of bricks and metal everywhere at the site, local TV footage showed. Other nearby buildings, including a mosque, also were damaged. Ambulances were rushed to the area.

No group immediately claimed responsibility, but suspicion immediately fell on the Pakistani Taliban and allied militant groups responsible for a wave of attacks that killed more than 600 people late last year -- a stretch of violence that appeared to be retaliation for a military offensive against insurgents along the Afghan border.

(With AP inputs)