Islamabad, Pakistan (CNN) -- A gun battle between security forces and Taliban militants raged on Monday morning inside a naval base in Pakistan -- more than 10 hours after attackers with guns and grenades stormed the compound in the coastal city of Karachi.
At least four naval officials were killed and seven others wounded in the fighting on the grounds of the Mehran base, said Pakistani navy spokesman Irfan Ul Haq.
He did not have the number of militants who died or were injured.
The Pakistani Taliban said the attack at the naval air station was to avenge the killing of innocent civilians. The group's spokesman, Ihsan Ullah, told CNN on Monday that Pakistani security forces are carrying out the killings on the instruction of the United States in the name of a "war on terror."
About 10 to 15 militants attacked the base about 11 p.m. Sunday. Two witnesses -- Amjad Bashir and Talha Hashmi -- reported at least 10 explosions in the subsequent hours.
Each blast was typically followed by a sustained exchange of gunfire, Hashmi said.
He said that several of the explosions -- thought to be the result of at least one military aircraft and a fuel tank catching fire and releasing plumes of smoke -- were particularly large.
The damaged plane is a P-3C Orion, according to Haq. Supplied by the U.S. government, the P-3C Orion is a "four-engine, turbo-prop, anti-submarine and maritime surveillance aircraft," according to the U.S. Navy's website.
The nation's military personnel responded with what Pakistani Interior Minister Rehman Malik called a "major operation" at the base, which is about 10 kilometers (6 miles) from Karachi's main airport.
According to the Pakistani navy's website, the Mehran base "is efficiently supporting day and night operational activities of all (naval aviation) squadrons." A host of courses are also offered on its grounds, from helicopter and air navigation instruction to sea survival.
The Pakistani Taliban represents a confederation of Taliban groups in northwestern Pakistan, where they are based. The group, which is headquartered in Quetta, is different from the Afghan Taliban, which has been focused on re-establishing the Islamic Emirate in Afghanistan. Both groups swear allegiance to Taliban leader Mullah Omar and have close ties to al Qaeda.
Karachi, which is considered the main commercial hub of Pakistan, has seen a drastic increase in political, ethnic and religious violence in recent months.
Just over three weeks ago, three people were killed and at least 20 others were injured when a hand grenade exploded at a gambling club in the southern Pakistani city.
The grenade was tossed into the club by one of two unidentified people riding past the facility on a motorbike, according to Javed Baloch, a senior police official in Karachi.
The Taliban said it was behind an April 28 roadside bombing on a main road through Karachi that left at least five dead and 10 injured.
Two days earlier, three were killed and more than 30 wounded when remote-controlled bombs detonated near two buses carrying Pakistani navy officials.
