ISLAMABAD , Pakistan ( CNN ) -- Three suspects were arrested after an explosives-packed van reduced a police building to rubble Wednesday in eastern Pakistan , killing 27 . The scene of an apparent suicide car bomb attack on a police building in Lahore on May 27 . The morning attack in Lahore -- Pakistan 's second-largest city -- also wounded more than 250 people , most of them police officers and staffers , authorities said . Fourteen of the dead included police officers . Three others were identified as bodies of `` terrorists , '' said City Commissioner Khusro Pervez . Immediately after the blast , police arrested two of the suspects , said City Commissioner Khusro Pervez . Local television showed the men being led away by officers . Sir Ganga Ram hospital , which was damaged by the explosion , was treating 128 victims . Authorities expected the death toll to rise as rescue workers picked through twisted metal and other debris from the building , looking for more bodies . Watch more on the attack » . The attack comes amid a Pakistani military offensive to rout militants from their haven in the northwestern part of the country . Baitullah Mehsud , the leader of the Pakistan Taliban , had threatened to target major Pakistani cities if the operations did not cease . `` The enemies of Pakistan are trying their very best to use every venue to destabilize the country , '' Interior Minister Rehman Malik told reporters Wednesday . The blast occurred on Mall Road near the city police headquarters and the high court . It is one of Lahore 's busiest areas . A passenger van , laden with explosives , broke through a security barrier and was headed toward the police building when guards opened fire to stop it , said Lahore 's district coordination officer , Sajjad Ahmed Bhutta . Watch rescue workers respond to the scene » . The two sides exchanged gunfire , with the attackers hurling grenades , said Faisal Gulzar , deputy police superintendent . The van exploded before it could reach the building . It was carrying an estimated 100 kilograms ( 220 pounds ) of explosives , Bhutta said . The impact was immense . The targeted building -- Building 15 -- collapsed . It housed the city 's rapid response team , which is dispatched during emergencies . At least 50 people were thought to have been inside the two-story building at the time , said police spokesman Ray Nazar Hayat . The police headquarters that sits adjacent to the building was also damaged . Motorcycles from a nearby dealership were strewed about , charred from the heat . The roof of four operating rooms caved at Sir Ganga Ram Hospital , with 40 medical staff members suffering minor wounds . Police waved away onlookers in vain . Many of them jumped over the collapsed walls of Building 15 to look for survivors . Semi-conscious officers in blood-stained uniforms were pulled from under wooden planks . No group immediately claimed responsibility for the attack , with suspicion falling on the beleaguered Islamic militants in the northwest who had vowed revenge . `` We 're doing our best , '' Malik , the interior minister , said of the offensive in the northwest . `` Please do not forget we 're in a state of insurgency . It 's a fight for our survival . We had two choices : We surrender our country or we save it for our next generation . '' Lahore is Pakistan 's cultural capital , far removed from the fundamentalist interpretation of Islam that is embraced in the north of the country , which borders Afghanistan . Still , it has sporadically been swept into widening Islamist violence that grips the country . In March gunmen hurled grenades and opened fire on officers at a police training center , killing at least seven cadets . The same month gunmen opened fire on a bus carrying members of the Sri Lankan national cricket team on their way to a stadium for a match . The attack wounded at least eight members of the team and killed a driver and six Pakistani police officers . `` Everywhere in the city is insecurity , '' Haris Nadeem , a student in Lahore , said Wednesday . `` You never know when a blast is going to occur or where . A shopping center ? A government office ? '' Still , said Saleem Khan , residents forge ahead . `` We will avoid places when they are crowded , but we ca n't change everything , '' he said . `` We ca n't stop going out of our houses . Life has to go on . '' CNN 's Ingrid Formanek and Saeed Ahmed and journalists Zeeshan Ali Taher and Naser Habib contributed to this report .
NEW : Three attackers among the dead , city official says . At least 27 killed , more than 100 wounded , according to officials . Fire reduced a building in Lahore to rubble . Car loaded with explosives detonated by building with at least 100 people inside .