Gunmen attacked Pakistan's naval aviation base on Sunday, starting fires, setting off explosions and fighting pitched gun battles inside one of the country's most heavily guarded military installations.
Officials said at least two people had been killed in the attack on PNS Mehran in the southern city of Karachi.
Between 15 to 20 gunmen entered the high-security facility before splitting up into smaller groups, setting off explosions and hiding in the sprawling facility.
Witnesses said they could hear gunshots and see smoke rising from the base.
"They were equipped with sophisticated weapons," said navy spokesman Commodore Irfan ul-Haq.
Another spokesman said that one P-3C Orion, a maritime patrol aircraft, had been destroyed. Gunmen storm Karachi military base - Telegraph
UPDATE: "The New York Times said that a mere 15 miles away from PNS Mehran, Pakistan was believed to keep a large depot for nuclear weapons that can be delivered from the air. "http://www.telegraph.co.uk/news/worldnews/asia/pakistan/8530101/12-killed-in-Karachi-naval-base-raid.html