Kabul (CNN) Desperate guests threw themselves off balconies to their deaths as gunmen roamed Kabul's Intercontinental Hotel firing and throwing explosives in a deadly siege that ended Sunday, an eyewitness tells CNN.

Afghan authorities say the attackers killed at least 18 people, including 12 foreigners, during the 12-hour standoff with security forces, although unconfirmed media reports put the toll much higher. At least four assailants also were killed.

The attackers were affiliated with the Pakistan-based Haqqani network, according to the Interior Ministry. The Taliban released a statement claiming responsibility.

Abdulhaq Omeri (front left) and other survivors at the Intercontinental Hotel after security forces ended the siege.

Omeri had been having dinner with friends -- including the Afghan general consul for the Pakistani city of Karachi -- in a fourth-floor suite when they were interrupted by loud banging on the door about 8:45 p.m. Saturday (11:15 a.m. ET).

Eleven hotel waiters rushed in saying the hotel was under terrorist attack.

Terrified, Omeri said they barricaded the door to the room with anything they could find. An hour later the attackers reached their floor, firing at doors to gain access.

"As soon as they broke the doors of the rooms with bullets, they threw a kind of explosive inside the room that after exploding burned down almost everything around it," he told CNN.

"We thought that it was the last moment of our lives. Two of the waiters and the nephew of the Afghan General Consul jumped out of the balcony to survive, but as they jumped from the fourth floor and the ground surface was concrete, they didn't make it alive on the ground.

"We lost the general consul himself in the room as a result of the explosion."

Desperate guests and staff trying to escape from burning #Kabul Intercontinental Hotel as siege enters 11th hour. pic.twitter.com/MZrty8WIa3 — TOLOnews (@TOLOnews) January 21, 2018

Omeri said survivors from his suite escaped via the balcony to the neighboring room whose residents had already been killed and burned by the terrorists.

"Then from there we moved to the next suite where we also found dead bodies. We all sat quiet on the balcony waiting for our death.

"We sat there for the entire night. During that time, I heard women and children screaming, men begging the attackers to spare their lives," he said.

"The worst one was when a man was screaming for help right next door to us, the attackers heard him and went into the room. I heard one of the attackers saying to the other one to shoot him. Then they shot him, and we never heard the man scream again."

Security forces arrive

Security forces near the Intercontinental Hotel after the attack.

Afghan security forces and NATO troops arrived at the building at 4 a.m., Omeri said. Afghan media described an increase in gunfire as they entered.

Some two hours later, soldiers arrived at the fourth floor where Omeri was shivering outside on the balcony.

Afghanistan's Interior Ministry said 153 people -- including 41 foreigners -- were eventually rescued from the hotel.

Omeri said one of the assailants had earlier tried to flush out survivors by claiming to be Afghan police and that when NATO special forces arrived they feared they could be attackers in disguise.

"According to what I saw there, the death toll must be very high. Seven people were killed right in front of my eyes," he said.

"The terrorists spent the whole night killing people especial on the third floor where they spent a big chunk of their time. We were constantly hearing the bullet-shot sound and explosions almost in every room. As the security forces got in late, the attackers had enough time to go door to door and kill people."

How the attack started

Omeri said one of the hotel waiters hiding with him on the balcony described how the attack began. The waiter said that six attackers had been involved, two of whom had taken a room on the hotel's second story.

"He told me that earlier in the day a big box was brought into the hotel building through the kitchen on the second floor. The waiter said that it looked suspicious, but he was told by one of his seniors that it was none of his business to ask questions about that box."

The waiter said that the attack was launched from three locations simultaneously, with two men opening fire in the restaurant where they had been dining, two men firing at security guards outside and the final pair beginning to kill guests on the second floor, Omeri said.

Warning

The Afghan Interior Ministry blamed the Haqqani network for the attack. The group is based in the Pakistani tribal area of Waziristan and known for its high-profile attacks on Western targets in Afghanistan. The network maintains close ties to al Qaeda and the Taliban, and seeks to reestablish Taliban rule in Afghanistan.

The US State Department had warned last week of a possible attack by extremist groups targeting Kabul hotels.

US Secretary of State Rex Tillerson issued a statement on Sunday condemning the attack.

Flames light up the sky after the Kabul Intercontinental Hotel was attacked in 2011.

"The United States stands with the government and people of Afghanistan," he said. "We remain firmly committed to supporting Afghan efforts to achieve peace, security, and prosperity for their country. Violence like what we witnessed yesterday has no place in Afghanistan or anywhere else in the world."

Pakistan's ministry of foreign affairs also issued a statement. "We reiterate our strong condemnation of terrorism in all its forms and manifestations. In our view, cooperation among the states is important for effectively combating and eliminating the scourge of terrorism," it said.

In June 2011, seven Taliban fighters attacked the same hotel over several hours. In the end, all seven, along with 11 other people , were dead.

The InterContinental Hotels Group developed the hotel, which opened in 1969. But the hotel has had no association with the group since the Soviet invasion in 1979, though it continues to use the name without connection to the international company.