KARACHI A massive explosion ripped through head office of the Crime Investigation Department (CID), located at a busy commercial street here on Thursday night, killing at least 18 people and injuring 120 others. The powerful blast brought down complete front portion of the building of CID located in the Red Zone of the metropolis near the Sindh Chief Ministers House. The intensity of blast was so severe that it was heard in a 15-kilometre radius. The bomb levelled the CID building and left about 40 feet across and 12 feet deep crater in front of it. According to bomb disposal experts, around 1,000-kg explosive materiel was used in the blast. The Chief Ministers House, Governors House, Qasr-e-Naz, three luxury hotels, the US Consulate and government offices are also located in the Red Zone. The blast razed the portion of three-storey building of CID to the ground. City Police Chief, Fayyaz Leghari, while talking to TheNation said that a truck loaded with explosives managed to enter CID operations office after an intense exchange of fire with the security guards. The police chief termed the incident a reaction of the arrests of terrorist affiliated with Lashker-e-Jhangvi, the CID made yesterday (Wednesday). The terrorists first resorted to heavy firing in the office of CID before detonating a massive explosive-laden truck, said Sindh Home Minister Dr Zulfiqar Mirza, while talking to media at the site of blast. He said that the attack appeared similar to the one that targeted Marriott Hotel in Islamabad. Inspector General of Police (IGP) Sindh, Sultan Salahuddin Babar Khattak, informed media persons that a truck with a Peshawar number plate reached the main gate of CID building then at least 20 suspects resorted to firing for at least 10 minutes. Later, they hurled crackers inside the CID building, killing the security guards deployed at the main gate. The provincial police chief further said the militants later entered the premises of building and detonated the vehicle. He added that the blast also damaged the residential area located around the CID office. IG Khattak confirmed that the attackers and senior officials of the CID remained unhurt in this incident. We heard different rounds of firing for several minutes and then a huge explosion, said an eyewitness. The roof of our house has collapsed, he added. A police constable, who survived the attack, said the entire operation was so swift that police had no time to react. The terrorists blew up the truck by the time we reached our guns to fight them, he said on the condition of anonymity. Ambulances and rescue teams rushed towards the blast site and shifted the bodies and injured to Jinnah Postgraduate Medical Centre and Civil Hospital. Heavy machinery was called to remove the debris and retrieve the possible survivors. In-charge of Jinnah Postgraduate Medical Centre Emergency Department, Dr Seemi Jamali, confirmed that the hospital had received 10 bodies and 90 injured people. According to television channels, Tehreek-e-Taliban Pakistan claimed the responsibility of the attack.