ISLAMABAD - A SUSPECTED suicide car bombing partly demolished a building at the police headquarters in Islamabad on Thursday, but the number of casualties was still unclear, police and security officials said.

Initial reports indicated that eight people were killed in the blast in the Pakistani capital, but a police officer later said that seven people were wounded in the attack.

The attack happened as intelligence and military chiefs were briefing lawmakers on the campaign against Islamist extremists, in a rare hearing at the parliament building about three kilometres from the explosion.

'We were lucky that almost the entire staff was on duty at parliament. All the people are accounted for and we have seven injured,' police inspector Ehsan Khan told AFP.

A senior police official speaking on condition of anonymity earlier said that eight people were killed but later said the situation was unclear.

A building at the complex, which contains training and residential facilities for police officers, partly collapsed after the attack, television footage showed. There was a large crater at the scene.

Another official said it was a 'suspected suicide car bomb attack'.

Ambulances rushed to the scene after the blast while a military helicopter hovered overhead, AFP reporters said.

'The blast was so powerful that it broke the windows and doors of our house,' said a resident who lives in the area, adding that people rushed to the police complex after the attack.

The blast comes less than three weeks after a suicide truck bombing at the Marriott Hotel in Islamabad, one of the worst terror attacks in Pakistan's history, in which 60 people were killed. -- AFP