Terror struck Lahore [Images] for the third time in two months when an explosive-laden vehicle, apparently targeting the Inter Services Intelligence headquarters, went off in the crowded Civil Lines area, killing at least 10 people and injuring over 150.

Police officials said 10 people have been killed but the privately run rescue organisation Edhi Foundation put the death toll at 35.

The explosive-laden pick up truck could not reach the ISI building and blew off at a barrier close to the complex. Reports said some suspects, who were detained in connection with the March 3 terror attack on the visiting Sri Lankan cricket team in Lahore, were inside the ISI office when the blast took place.

The blast occurred near the Mall Road in the Civil Lines area that houses several buildings including the city police headquarters. The ISI building sustained some damage due to the impact of the explosion, witnesses said. Pakistani television channels showed images of two damaged buildings and several charred cars.

There were also reports of sporadic firing in the vicinity. The channels said seven bodies have so far been recovered from the debris.

Thick smoke was seen billowing into the sky soon after the explosion rocked the metropolis. Geo TV said window panes of several buildings near the blast site were shattered.

Television footage showed several injured and stunned bystanders with blood splattered around. The police said the blast destroyed several vehicles and many people suffered shrapnel injuries.

The area has been cordoned off as ambulances rushed to scene of the explosion. President Asif Ali Zardari [Images] ordered a probe into the attack, which comes close on the heels of the Pakistan government's stepped up offensive against the Taliban [Images], in the North West Frontier Province.

The blast comes less than two months after the attack on the police academy at Manawan, close to Lahore, on March 30 this year, when armed gunmen laid a siege resulting in the deaths of 10 people including eight policemen.

Lahore was also the scene of an attack on the visiting Sri Lankan cricket team on March 3, in which eight people, including six police officials, were killed and six cricketers were injured.