At least 11 people were killed and 68 injured when a suicide bomber rammed his explosive-laden car into a building housing the office of an investigative agency in Pakistan's eastern city of Lahore on Monday, security officials said, dpa reported.
The blast brought down the building located in Model Town, an upmarket residential area of the city. Rescue workers were searching for dozens of missing employees of the Federal Investigation Agency (FIA).
"It was a car bombing. The terrorists detonated the explosive-laden vehicle at the main gate of the building," said Tariq Saleem Dogar, the police chief for Punjab province of which Lahore is the capital.
Television footage showed rescue workers trying to pull out bodies and injured people from the piles of bricks and metal. Officials said around 600 kilograms of explosive material were used in the bombing.
The bombing, which was heard across the city, also damaged several nearby buildings and vehicles in Model Town, where a number of politicians live, including former prime minister Nawaz Sharif.
"We were attending class when a huge blast took place. It shattered window glass and I was thrown several feet," said a student at the Quran Academy, a nearby Islamic seminary.
A woman and a schoolgirl were among the 11 people killed in the attack, Lahore's top civil administrator Khusro Pervez told reporters at the Jinnah Hospital, where many of the 68 injured, including 13 women, were taken.
Pakistani Aaj television reported that five FIA personnel perished in the strike.
No group immediately claimed responsibility, but the officials suspected Taliban and al-Qaeda linked militant groups, who have intensified attacks on security officials and civilians since government forces launched a major offensive in South Waziristan near the Afghan border in mid-October.
The FIA has been involved in the investigation of terror-related incidents. Last year, two suicide bombers struck the FIA offices, killing 26 people.