LAHORE: A suicide car bomber struck a building where police interrogate high-value suspects in Pakistan's eastern city of Lahore on Monday, killing at least 11 people and wounding 61 more including women taking children to school, officials said.

The attack broke what had been a relative lull in major violence in Pakistan, a nuclear-armed country reviled by some militant groups for its alliance with the U.S. It also showed that insurgents retain the ability to strike the country's heartland, far from the Afghan border regions where al-Qaida and the Taliban have long thrived, despite army offensives aimed at wiping them out.

No group immediately claimed responsibility, but suspicion immediately fell on the Pakistani Taliban and allied militant groups. Those groups are believed responsible for a wave of attacks that killed more than 600 people starting in October, including several in major Pakistani cities. More recent attacks have been smaller and confined to remote northwest regions near Afghanistan.

The bomb blast Monday comes amid reports of a Pakistani crackdown on Afghan Taliban and al-Qaida operatives using its soil. Among the militants said to have been arrested is the Afghan Taliban's No. 2 commander, Mullah Abdul Ghani Baradar.

The explosion went off outside a Punjab province police building, police official Zulfikar Hameed said. TV footage showed a huge crater in the ground where the blast seemed to have originated.

"This place was used to interrogate important suspects, but presently there was none such suspect, but more then 40 staff were manning the place," Lahore police chief Pervez Rathore said.

Noorul Huda, a student at a nearby religious school, was in his first class when the blast shook the area, he told TV reporters.

"With the huge bang, blocks and pieces of the roof fell upon us and six of us were wounded," said the young man, who suffered a head injury that was covered by a bloodstained cloth. "It was total chaos outside and people were running and crying for help."

Residents in the neighborhood had filed complaints urging authorities to move the unmarked interrogation facility out of the area so the street wouldn't become a target for an attack, said Mohammad Musharraf, who lives nearby.

"My whole house was shaken and I thought it was an earthquake," he said. "A window dislodged and fell on my son, fracturing his arm."

Lahore government official Khusro Pervez said 11 people had died and several of the 61 people wounded were in critical condition. It appeared the suicide bomber rammed his explosives-laden car into the perimeter wall.

Hospital official Jawed Akram said the dead included at least one woman and a young girl, apparently part of a group heading to a school. Several women were wounded, Pervez said.

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

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

Militant attacks in Pakistan frequently target security forces, though civilian targets have not escaped. During the bloody wave of attacks that began in October — coinciding with a major army ground offensive against the Pakistani Taliban in South Waziristan tribal area — Lahore was hit several times.

In mid-October, three groups of gunmen attacked three separate security facilities in the eastern city, a rampage that left 28 dead. Twin suicide bombings at a market in Lahore in December killed nearly 50 people.