Militants late Sunday stormed a naval base in Pakistan's largest city, Karachi, triggering a battle with government commandos that stretched into Monday morning in what was believed to be a revenge attack for the killing of Al Qaeda leader Osama bin Laden.
Initial reports suggested between 10 and 15 militants were inside the base, though by early Monday authorities were reporting that perhaps as many as 20 to 25 terrorists had carried out the attack on the Mehran Naval Station in Karachi, the country's largest port.
As many as 100 Pakistani commandos had surrounded the militants, who were dressed in black and armed with AK-47 automatic rifles, rocket-propelled grenade launchers and hand grenades, according to Pakistani television reports. Pakistani military helicopters hovered overhead.
The soldiers and commandos exchanged gunfire with the militants through the night. Witnesses heard at least 20 explosions at the base as the battle raged.
Speaking to reporters in Karachi, Interior Minister Rehman Malik condemned the assault.
"The Taliban and Al Qaeda have announced that they will attack Pakistani installations and of course the armed forces," Malik said. "They have done that. Pakistan is suffering, Pakistan is a victim, but we have the courage and resolve to fight."
That a team of militants was able to storm a major military installation is yet another source of embarrassment for the country's military leaders, who were already under fierce criticism from Pakistanis for allowing U.S. military helicopters to fly deep into Pakistan to carry out the raid that killed Bin Laden.
The attack may also raise new concerns in the West about the Pakistani military's ability to secure its nuclear arsenal from Islamic militants.
Government officials said two U.S.-supplied surveillance aircraft, P-3C Orions, kept in a hangar at the base had been destroyed in the fighting.
As of early Monday, five militants and four Pakistani navy commandos and one Pakistani ranger had been killed, authorities said.
The brazen, commando-style attack was the country's worst since militants stormed the army headquarters in the garrison city of Rawalpindi and took hostages in 2009, setting off a 22-hour standoff that left 23 dead, including nine militants. It comes three weeks after a team of U.S. commandos slipped into the military city of Abbottabad, near the capital, and killed Bin Laden.
The Pakistani Taliban had vowed to avenge the Al Qaeda leader's killing with attacks on both Pakistanis and Americans. Their first major retaliatory strike came May 13, when twin suicide bomb blasts killed at least 80 paramilitary recruits in the northwestern town of Shabqadar.
On Friday, a car bombing targeted two U.S. Consulate vehicles in the northwestern city of Peshawar, killing a Pakistani bystander and slightly injuring Americans inside the cars.