A suicide attacker drove an explosive-packed pick-up truck into the compound of the Federal Investigation Agency office located on Temple Road and blew himself up at 9.30 AM, killing at least 19 people and leaving the seven-story building in shambles, officials said.

In the second near-simultaneous blast in the Punjab capital, two suicide bombers drove a pick-up truck into the compound of a house in Model Town residential area that had been rented by an advertising agency and blew themselves up.

Bilawal House, which is owned Zardari, and the residence of Lahore city nazim Amir Mehmood are located in the vicinity of the house that was attacked.

Besides the two bombers, the blast killed two children of the gardener who worked at the house. It created a seven-foot crater and smashed windows of buildings within a radius of 100 metres, witnesses said.

Two persons, including the gardener, were seriously injured in the blast, said police officer Azmat Gondal.

"The suicide attackers drove into the house and blew themselves up before the guard at the gate could stop them. We do not know as yet why this house was targeted," Gondal said.

Reports said the suicide bombers might have been trying to target the nearby residence of an army officer. Last week, two suicide bombers targeted the Navy's War College on Mall Road, killing seven persons while the country has been rocked by six major blasts since the Feb 18 polls.

FIA Director Chaudhry Manzoor said at least 10 employees of the organisation were killed.

The city administration declared the FIA office as unsafe and ordered everyone except rescue workers to leave the structure.

Officials said they had recovered the close circuit cameras and videos which would be analysed.

Over 100 FIA employees had already reported for work when the blast occurred destroying the entire front of the building. Walls and stairs collapsed, posing problems for rescue workers trying to remove the injured and dead from the structure.

Aaj News channel reported the suicide attacker's head had been found by police and sent for DNA tests.

Nearly 35 kg of explosives were packed into the truck, officials said.

The explosion also triggered fires in the FIA office and CNG tanks of cars parked in the parking lot. At least 12 cars were destroyed and several of them exploded.

The attack created panic in the nearby Mall Road area, a bustling commercial area where shops and commercial complexes were opening for the day when the blast rocked the area.

The explosion shattered the windows of nearby buildings and houses. Students of the Sacred Heart School, located near the FIA office, were evacuated.

Pakistan has been rocked by a wave of suicide attacks, especially those targeting military, since last year which are being blamed on the local Taliban who are battling security forces in the countries restive tribal areas.