KARACHI: Militants attacked a naval base in the Pakistani city of Karachi late Sunday, rocking the base with fiery explosions and battling commandos sent in to subdue the attackers, security officials said, a daring raid by anti-government forces. Four people died and an airplane was destroyed, navy spokesman Salman Ali said, but the total number of casualties was unclear. Many ambulances were being held back because of the fighting inside the base that was still going on more than 2-1/2 hours after the attack began on Pakistani Naval Station Mehran. The strike appeared to be one of the most brazen to hit the country in several years of relentless violence by Al-Qaeda and Taliban militants. It came just under three weeks after the death of Osama Bin Laden in an American raid in the northwest city of Abbottabad, an event extremists have vowed to avenge. The unilateral American raid triggered a strong backlash against Washington, which is trying to support Pakistan in its fight against militants, as well as rare domestic criticism against the armed forces – the most powerful institution in the country – for failing to detect or prevent the operation. The attack began with at least three loud explosions heard by people who live around the naval base. It was unclear exactly what caused the explosions, but they set off raging fires that could be seen from far in the distance. Authorities sent in several dozen navy and police commandos to battle the attackers, who responded with gunfire and grenades, said a senior security official. At least one airplane – a P-3C Orion, a maritime surveillance aircraft – was destroyed, another official said. Reports said a team of American technicians were working on the aircraft at the time of the strike, but US Embassy spokesman Alberto Rodriguez said no Americans were on the base. No group has claimed responsibility for the attack. But the Pakistani Taliban, an Al-Qaeda allied network which has previously launched attacks in Karachi, has pledged to retaliate for the death of Bin Laden, and has claimed responsibility for several bloody attacks since then. – Agence France