Taliban gunmen disguised as police guards attacked a terminal at Pakistan's busiest airport Sunday with machine-guns and a rocket launcher during a five-hour siege that killed 18 people as explosions echoed into the night, officials said.

Pakistan's Taliban claimed responsibility for the attack, saying it was revenge for the army's air strikes in areas along the Afghan border where the insurgents are based. 

"We carried out this attack on the Karachi airport and it is a message to the Pakistan government that we are still alive to react over the killings of innocent people in bomb attacks on their villages," said Shahidullah Shahid, a Taliban spokesman.

The claim further diminished prospects for a resumption of government-led peace talks with the Taliban. Those talks floundered in recent weeks and the Taliban have called off a cease-fire they declared during negotiations.

Since then, Pakistani troops have carried out airstrikes in the country's troubled northwest to target militant hideouts, killing dozens of suspected militants. Residents claim several civilians were also killed in the strikes.

Attack was 'well thought out'

The airport attack began late Sunday and continued on into the dawn hours of Monday in Karachi, a sprawling port city on Pakistan's southern coast, although officials said all the passengers had been evacuated.

During the course of the attack, heavy gunfire and multiple explosions could be heard coming from the terminal, used for

Pakistan airport attacks

A Pakistani paramilitary group claimed Monday that the group of Taliban insurgents that attacked the airport was made up mostly of foreign fighters, including extremists from Uzbekistan. (Athar Hussain/Reuters)

VIP flights and cargo, as militants and security forces battled for control. A major fire rose from the airport, illuminating the night sky in an orange glow as the silhouettes of jets could be seen. 

The deadly operation was carried out by 10 militants, said the Chief Minister of Sindh province, Qaim Ali Shah.

"They were well trained. Their plan was very well thought out," he told reporters. He said they intended to destroy some of the aircraft and buildings but were not able to.

The spokesman for the Pakistani military, Gen. Asim Bajwa, said on Twitter that no aircraft were damaged and that as a precautionary measure, security forces were sweeping the airport before operations would be returned to the Civil Aviation Authority and airport police.

Gunmen strapped with explosives

At least some of the gunmen wore the uniforms of the Airport Security Force that protects the nation's airports, said an official who briefed journalists near the airport. He said all were strapped with explosives. He said one of them tried to capture a vehicle used by the Civil Aviation Authority and when a guard shot at him, the explosives strapped to his body went off. The official said another attacker also blew up after being shot at by security forces.

The official described himself as being with one of the country's intelligence agencies but declined to give his name.

After storming into the airport grounds, gunmen took shelter in two sections of the airport, said senior police officer Ghulam Qadir Thebo. 

'The blast you heard a little while ago was when our police party went to pick up a body (and) one of the attackers blew himself up.'- Senior police officer Ghulam Qadir Thebo

"The blast you heard a little while ago was when our police party went to pick up a body (and) one of the attackers blew himself up," Thebo said

Authorities seized four machine-guns and a rocket launcher, Thebo said. He said the billowing smoke and flames was from oil that had caught fire.

Pakistan Karachi airport attack

Pakistan army troops arrive at Karachi airport following an attack by unknown gunmen disguised as police guards who stormed a terminal used for VIPs and cargo, Sunday night n Pakistan. (Fareed Khan/The Associated Press)

Dr. Seemi Jamali from Jinnah Hospital in Karachi said 11 bodies had been brought to the hospital from the fighting. She said nine were Airport Security Force personnel, one was a member of the paramilitary Rangers, one was from the police, one was an employee of the Civil Aviation Authority and another was from the state-run Pakistan International Airlines.

Airport remains closed

Authorities diverted incoming flights and suspended all flight operations. A spokesman for the Civil Aviation Authority said the airport would be closed until at least Monday night.

Sarmad Hussain, a PIA employee, told The Associated Press he was at the airport at the time of the attack.

"I was working at my office when I heard big blasts — several blasts — and then there were heavy gunshots," Hussain said. He said he and a colleague jumped out of a window to get away, and his colleague broke his leg.

Karachi is Pakistan's largest city and has been the site of frequent militant attacks in the past. It is the country's economic heart and any militant activity targeting the airport likely would strike a heavy blow at foreign investment in the country. 

Pakistan

Fire illuminates the sky above a Karachi airport terminal where security forces fought with attackers early Monday morning. (Shakil Adil/Associated Press)

In May 2011, militants waged an 18-hour siege at a naval base in Karachi, killing 10 people in an assault that deeply embarrassed the armed forces.

There was no immediate claim of responsibility for Sunday night's attack. Pakistan's government has been trying to negotiate a peace deal with local Taliban fighters and other militants mostly based in the northwest who have been waging war against the government. But the talks have had little success, raising fears of a backlash of attacks across the country.

Security officials in Karachi had feared that if the talks broke down, their city would be a likely spot for any militant retribution. The Pakistani Taliban and their allies increasingly are gaining a foothold in Karachi.

'We are used to this'

In the suicide bombing, four bombers targeted Shia pilgrims staying at a hotel in the town of Tuftan near the Iranian

border, said Baluchistan province Home Minister Mir Sarfraz Bugti. One bomber was killed by security officials travelling with the pilgrims, but the other three managed to get inside the hotel where they blew themselves up in an attack that also wounded 10 people, he said.

It wasn't immediately clear whether there was a connection between the airport assault and the Baluchistan attack. But the attacks were sadly familiar for Pakistan, which has seen thousands killed by militants in recent years.

Shahid Ali, who dropped his mother and father off at the airport prior to the attack, said they were onboard a flight when the attack began. Ali said the flight, heading to Iraq, later returned to the terminal without being told what was going on. He said his parents joined other passengers waiting in a lounge.

He said his parents were not panicked.

"We are used to this," Ali told the AP.

With files from Reuters