The fight between a group of militants and the armed forces that broke out late Sunday night at an air force base in Pakistan's southern port city of Karachi is still going on, reported local media.

Fire and smokes erupt from a Pakistan's military air base after an attack by militants in southern Pakistan's Karachi on May 23, 2011. [Xinhua]

Gunmen have attacked a military base in the Pakistani city of Karachi, killing at least 11 soldiers, BBC quoted Pakistani officials.

The attackers are now holding hostages, including Chinese military personnel, at the Mehran naval aviation base, BBC reported.  

As for the casualties on the side of the terrorists, some local media reported that about five terrorists have been killed as two airplanes including one U.S.-made P-3C Orion aircraft which is mainly for reconnaissance purpose were damaged.

At least 10 to 15 terrorists armed with automatic weapons, rocket launchers and handgrenades are involved in the attack, said most of the local media reports. But one local media report put the number of the attackers at about 20 to 25.

No officials figures regarding the number of terrorists have been released as media people are not allowed to enter the area where the firing occurred.

Up till now, over 20 explosions have been reported within the Faisal base of Pakistan Air Force.

Local media reports quoted military sources as saying that the strategy of the armed forces who have completely surrounded the air force base is to capture the terrorists alive so that they can know who are behind these attack.

According to the latest reports, the terrorist have retreated into a building within the air force base and are holding an unknown number of hostages as human shield to fight back the navy commandos, rangers and other armed forces. Over 3,000 armed forces have reportedly been dispatched to the air force base which is under terrorist attack.

Helicopters are said being hovering over the area to monitor the situation there.

Shortly after the attack at the air force base was reported, Pakistani Prime Minister Yousurf Raza Gilani has ordered the interior minister to fly down to Karachi to bring the situation under control as quickly as possible with the help of the army and conduct an investigation into the incident.

Some local media reports criticized the army for the failure to prevent the terrorists from entering the air force base.

It is still an unanswered question as how these terrorist could manage to enter the heavily guarded military air base. Some local media reports that the terrorists entered the air force base through a sewage system while others said that they came into the air force base in black vehicles.

The latest news coming in quoted the Pakistani interior minister as saying that the terrorists have entered the air force base from three sides.

Not long after the blasts and firing were reported at the air force base, Pakistan Taliban (TTP) claimed the responsibility for the attack.

Sunday night's attack at a military air force is reported to be the biggest attack on the armed forces in Pakistan. Most local watchers believe that the attack could be related to the killing of Osama bin Laden.

Both Pakistan and al-Qaida have vowed to the avenge the killing of the al-Qaida chief bin Laden by the U.S. special force in Pakistan early this month by threatening to launch attacks in Pakistan, the United States and the other parts of the world.

On May 13, Pakistan Taliban launched two suicide bomb attacks at an armed border police training center in the country's northwestern city of Charsadda, which reportedly killed 98 people and injured more than 140 others.

A few days ago, Pakistan Taliban planned a road-side bomb aimed at killing the people working for the U.S. consulate in Peshawar. However, due to the poor timing of the bomb, only two U.S. consulate employees were slightly injured in the bomb attack.

Local analysts said more attacks could follow in the near future. And something even bigger than the previously mentioned attacks could happen in Pakistan, said one local analyst, who declined to be named, adding that the targets could be important government organizations or important political figures.

Massive attacks on civilians or important infrastructure such as railways and airports are also possible, said the analyst, adding that the terrorists will not stop attacks until they have fully demonstrated their existence and muscles.