International officials confirmed Wednesday that a brazen attack by suicide bombers on a popular hotel in Afghanistan that left 19 dead was the work of the Haqqani network, a Pakistan-based insurgent group that are closely allied with the Taliban.

"We have intelligence indicators linking this failed terrorist attack to the Haqqani network," international officials told Fox News.

Eight insurgents stormed the Western-style Inter-Continental hotel in Kabul Tuesday night, setting of explosions and exchanging gunfire with authorities for hours until pressure from Afghan snipers and a NATO helicopter forced three of the remaining bombers to blow themselves up.

Hours later, an injured suicide bomber holed up in one of the hotel rooms detonated his explosives, signaling an end to the fight.

Eleven Afghan civilians -- all workers at Kabul’s Inter-Continental hotel -- were killed, along with two policemen. Thirteen others were wounded, but none of the hotel’s guests were killed.

The attackers were heavily armed with machine guns, anti-aircraft weapons, rocket-propelled grenades, hand grenades and grenade launchers, the Afghan officials said.

The 101 Asmayee Police Headquarters Forces and other Afghan Special Police Forces led the fight against the insurgents, the Afghan Ministry of Interior said in a release.

"The response of Afghan police clearly demonstrates the ANSF's ability to react to and deal with security incidents in Kabul. This was a complex and deliberate attack that had the potential to become a far more serious incident," an International Security Assistance Force official told Fox News.

Afghan police battled the assailants throughout the night with machine-gun fire and rocket-propelled grenades as tracer rounds went up over the blacked-out building.

"Afghan forces handled this operation," the ISAF official said. "The Afghans did well, supported by Afghan snipers on a NATO helo [helicopter]."

The NATO helicopter later flew over the roof of the hotel, prompting three of the attackers to blow themselves up “in an act of desperation,” an international official based in Kabul told Fox News.

Multiple explosions were heard in the initial attacks, where two bodies could be seen at the hotel's entrance.

Associated Press reporters at the scene said another two blasts -- about a minute apart -- occurred around 2:30 a.m. Wednesday.

The police then secured the area around the hotel, which is one of Kabul's most heavily guarded.

The attack occurred on the eve of a conference about transferring responsibility for security from foreign to Afghan forces by the end of 2014. Some conference attendees were staying at the hotel but were not hurt.

Nazar Ali Wahedi, chief of intelligence for Helmand province in the south, called the assailants "the enemy of stability and peace" in Afghanistan.

"Our room was hit by several bullets," said Wahedi, who is attending the conference elsewhere in the capital. "We spent the whole night in our room."

An Afghan Interior Ministry spokesman confirmed that both foreign and Afghan guests were staying at the hotel.

Jawid, another guest, said the attack occurred as many people were having dinner in the hotel restaurant. He says he heard gunfire throughout the several story building.

"I was running with my family," he said. "There was shooting. The restaurant was full with guests."

A State Department official told Fox News that all chiefs of mission personnel are accounted for in the country, including all U.S. citizens currently working for the embassy in Kabul.

Taliban spokesman Zabiullah Mujahid claimed responsibility for the attack in a telephone call to The Associated Press.

Mujahid later issued a statement claiming that Taliban attackers killed guards at a gate and entered the hotel.

"One of our fighters called on a mobile phone and said: 'We have gotten onto all the hotel floors and the attack is going according to the plan. We have killed and wounded 50 foreign and local enemies. We are in the corridors of the hotel now taking guests out of their rooms -- mostly foreigners. We broke down the doors and took them out one by one."'

The Taliban often exaggerate casualties from their attacks.

U.S. military officials have said the Haqqani network is the most dangerous militant group battling foreign forces in Afghanistan.

The U.S. has repeatedly asked Pakistan to launch an offensive against the network, but the military has said that its forces are stretched too thin by other operations in the tribal areas.

The Inter-Continental -- known widely as the "Inter-Con" -- was once part of an international chain. But when the Soviets invaded Afghanistan in 1979, the hotel was left to fend for itself.

The Inter-Continental, which opened in the late 1960s, was the nation's first international luxury hotel. It has at least 200 rooms.

It was used by Western journalists during the U.S.-led invasion of Afghanistan in 2001 and has been targeted before.

On Nov. 23, 2003, a rocket exploded nearby, shattering windows but causing no casualties.

Twenty-two rockets hit the Inter-Con between 1992 and 1996, when factional fighting convulsed Kabul under the government of Burhanuddin Rabbani. All the windows were broken, water mains were damaged and the outside structure pockmarked. Some, but not all, of the damage was repaired during Taliban rule.

Attacks in the Afghan capital have been relatively rare, although violence has increased since the May 2 killing of Usama bin Laden in a U.S. raid in Pakistan and the start of the Taliban's annual spring offensive.

On June 18, insurgents wearing Afghan army uniforms stormed a police station near the presidential palace and opened fire on officers, killing nine.

Late last month, a suicide bomber wearing an Afghan police uniform infiltrated the main Afghan military hospital, killing six medical students. A month before that, a suicide attacker in an army uniform sneaked past security at the Afghan Defense Ministry, killing three people.

Other hotels in the capital have also been targeted.

Fox News' Jennifer Griffin, The Associated Press and Newscore contributed to this report.