"We have four dead and five wounded but the number could rise," a security official, who declined to be identified, told Reuters.
Senior police official Tahir Naveed said attackers were fighting with base personnel. TV footage showed fire and a cloud of smoke. Private TV channel said a four-engine naval aircraft was on fire. On April 28, suspected militants detonated a roadside bomb in Karachi, killing four members of the navy, the third attack on the navy in a week. The attack came two days after two bombs hit buses carrying navy personnel, killing four people and wounding 56. Taliban insurgents took responsibility for the twin attacks.
In October 2009, Taliban militants beseiged the army headquarters in the garrison city of Rawalpindi for two days, killing 22 people and raising serious questions over why it took the military so long to put down the assault.
AP adds: 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 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, speaking on condition of anonymity because of the sensitivity of the issue. At least one airplane a P-3C Orion recently given to Pakistan by the US was destroyed, he said.
US Embassy spokesman Alberto Rodriguez said no Americans were on the base at the time of the attack. No group has claimed responsibility for the attack. But the Pakistani Taliban, which has previously launched attacks in Karachi, has pledged to retaliate for the death of Osama bin Laden in an American raid on May 2 in Abbottabad.
Prime Minister Yousuf Raza Gilani condemned Sunday's attack, saying such a ``cowardly act of terror could not deter the commitment of the government and people of Pakistan to fight terrorism.'