Gunmen have attacked a military base in the Pakistani city of Karachi, killing at least 11 soldiers, officials say. The attackers are now holding hostages, including Chinese military personnel, at the Mehran naval aviation base. Eight hours after the incident began, blasts and gunfire were heard as security forces brought in more troops and tackled the militants. The Pakistani Taliban says it is responsible for carrying out the attack. "It was the revenge of martyrdom of Osama Bin Laden. It was the proof that we are still united and powerful," Ehsanullah Ehsan told Reuters news agency. He said the attackers had enough food and ammunition to "fight and survive for three days". The Taliban have vowed to avenge the killing of Bin Laden by US special forces on 2 May. They have carried out several attacks since then. On Sunday evening at 2230 (1730 GMT) militants stormed three hangars housing aircraft at the Mehran base, according to officials. Interior Minister Rehman Malik said: "We have been able to confine them to one building and an operation is underway either to kill or capture them." Their first targets were aircraft parked on the tarmac and equipment in nearby hangers, says the BBC's Syed Shoaib Hasan at the scene. Eyewitnesses say the militants used rocket propelled grenades to damage and destroy several warplanes. These included the Pakistan navy's premier anti-submarine attack jet - the US made P-3C Orion. At least two of these multi-million dollar aircraft were set ablaze. The gunmen then opened indiscriminate fire, killing several naval personnel as they carried their deadly raid into the heart of the base. Subsequently, navy commandos and marines launched a counter assault. Dozens of heavily armed army reinforcements also arrived to provide cover. Some of the militants have now been killed, officials say. The remaining gunmen have taken several officials, including Chinese military personnel, hostage inside a building. Security officials say commandos are now being sent in to clear this area. At dawn on Monday, three loud blasts were heard, followed by gunfire. "The operation still continues. It is not over yet," one security official told Reuters news agency. On Friday the Taliban bombed a US consulate convoy in Peshawar, killing one Pakistani. Other attacks by Pakistani militants this month include a raid on a security post that killed two police in the north-west and a twin suicide bombing at a paramilitary police training centre. Source: BBC