Karachi, Feb 18 : At least three attackers were killed and 10 people wounded on Friday night when a group of terrorists opened fire at the headquarters of Karachi police in south Sindh province, officials said. The attack happened at around 7:10 p.m. local time when eight to 10 terrorists opened fire and hurled hand grenades at the Karachi police chief's office near the Saddar area of Karachi, Deputy Inspector General of south zone Karachi Irfan Baloch told media. He said four floors of the building had been cleared in the operation jointly launched by the Pakistan Army, paramilitary rangers and police, adding that during the clearance operation, a suicide bomber blew himself up on the fourth floor, partially damaging the building, Xinhua news agency reported. The powerful explosion also shattered the window glasses of nearby buildings, said the police. A heavy contingent of police and rescue teams reached the scene and cordoned off the area. Police also sealed off traffic on the main artery Shahrah-e-Faisal, where the building is located. Eyewitnesses told the news agency that the lights of the building under attack had been turned off, while gunshots and multiple explosions could be heard. Several police personnel were inside the office when the attack took place, said the police, adding that the attackers equipped with heavy weapons managed to enter the third and fourth floor of the building. The banned Tehrik-e-Taliban Pakistan claimed responsibility for the attack. In a statement issued Friday evening, it said the Karachi police office was the target of the attack. Pakistani Prime Minister Shahbaz Sharif strongly condemned the terrorist attack, appreciating the police and security forces for their effective action against the terrorists. "Terrorists once again targeted Karachi but this kind of cowardly act could not weaken the resolve of police and law enforcement agencies. The whole nation stood with police and security institutions ... collective efforts needed to root out the menace of terrorism," the Prime Minister said. /IANS