Investigators probed whether Al Qaeda was behind twin homicide attacks that killed 27 people as a new government prepared to take office, officials said Wednesday.

The bombings were the first major terrorism attacks since the parties of slain opposition leader Benazir Bhutto and another former premier, Nawaz Sharif, announced Sunday they would form a coalition government and try to cut the powers of U.S.-backed President Pervez Musharraf.

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Tuesday's blasts happened about 15 minutes apart in different districts of Lahore, Sharif's stronghold. The first tore the facade from the seven-story Federal Investigation Agency building as staff were beginning their work day.

While Al Qaeda-linked militants in Iraq have regularly used vehicles to launch massive attacks on buildings, such damage has rarely been inflicted on a government building in Pakistan.

Provincial police chief Azhar Hasan Nadeem said it was not yet clear if Al Qaeda was involved in the attack.

"Of course they have a huge organization, and they have a very vast network, but it would be premature to pinpoint exactly as to which particular organization is responsible," Nadeem told reporters Wednesday in Lahore.

A senior police investigator, Tasadaq Hussain, said efforts were under way to trace and capture those who orchestrated the attacks.

Rizwan Nasir, the head of the provincial ambulance service, said three more people wounded in the blasts had died, bringing the death toll to 27. He said eight patients remained in critical condition. In all, officials have said that more than 200 people were wounded in the attacks.

An explosives-packed vehicle drove into a parking lot and detonated close to the FIA building — which houses part of a police anti-terrorism unit — devastating offices on the lower floors and blowing out the walls around a stairwell.

Grainy footage from a surveillance camera shown on the private Aaj television channel showed the small truck running over a guard and barreling through the unlocked gate seconds before the blast.

A similar attack flattened the office of an advertising agency in an upscale suburb near a house belonging to Bhutto's widower.

Officials declined to speculate about whether Asif Ali Zardari's residence, located less than 50 yards away, was the intended target. Zardari, who succeeded Bhutto at the helm of her party, was in the capital, Islamabad, at the time.

Pakistan has suffered at least seven homicide attacks since the Feb. 18 elections, a landmark on the country's return toward democracy after more than eight years of military rule.

The spike in violence — and its spread from the regions along the Afghan border to relatively peaceful Lahore — has prompted some Pakistanis to question Musharraf's approach to countering Al Qaeda and the Taliban. Musharraf's opponents say punitive military action has helped militants recruit more supporters and prompted more attacks.

Musharraf condemned the "savage" bombings and said in a statement that the government would continue to fight terrorism "with full force."

But some enraged Lahore residents blamed the president. They gathered in small groups Tuesday on the city's main Mall Road, chanting "Musharraf is a dog! Musharraf is a pimp!"

Also Wednesday, Bhutto's party said that the remains of up to 20 victims of a homicide bombing on her homecoming parade last October will be buried at her tomb. The attack in Karachi killed more than 150 people among a huge crowd of supporters welcoming Bhutto back from years in exile. Bhutto survived only to die in another homicide attack in December.

In Pakistan's northwest, a government official said that a mortar shell struck a house during fighting between security forces and militants in the northwest, killing five civilians.

The battle broke out Tuesday after a bomb exploded near Pakistani troops as they collected water from a stream in Bajur, a tribal region bordering Afghanistan, said local government official Mohammed Jamil Khan. He said it was unclear who fired the shell onto the house.

In the northern Swat valley, two police explosives experts died Wednesday while trying to defuse a roadside bomb, said Mohib Ullah, a local police official.

The army also said Wednesday that its forces arrested five suspected militants and seized a weapons cache in Swat, where they have been battling supporters of a pro-Taliban cleric for months.