A powerful bomb ripped through a police complex in the city of Lahore on Wednesday, claiming at least 30 lives and injuring some 250, the first major attack since Pakistani forces launched an offensive against the Taliban.

A car bomb outside a police emergency call center and the adjoining city police headquarters, at 10:30 a.m. local time, reduced the buildings to rubble. Dozens could yet be found under the debris. The local office of Pakistan's premier spy agency, Inter-Service Intelligence, located nearby, was also badly damaged.

A month ago, the army started an operation against Islamic extremists in the north west, in the Swat valley and neighboring districts. Commentators had previously expressed surprise that there had been no big reprisal so far. Lahore, the main city of the country's most populous province and a metropolis regarded as the cultural heart of Pakistan, suffered two terrorists attacks in March, one on a visiting cricket team and another on a police academy.

"I believe that anti-Pakistan elements, who want to destabilize our country and see defeat in Swat, have now turned to our cities," Interior Minister Rehman Malik told reporters.