Updated at 11:45 a.m. ET

Gunmen attacked an upscale hotel in Kabul, Afghanistan, on Saturday night, killing at least 18 people, trapping hundreds of guests and setting off a firefight with Afghan security forces that lasted more than 13 hours.

Officials don't know how many staff and guests were inside the Intercontinental Hotel when the attack began around 9 p.m. Saturday local time, but Afghanistan's interior ministry says at least 150 people were rescued, including 41 foreigners, according to The Associated Press.

Interior ministry spokesperson Najib Danish told the news service that the assault ended early Sunday afternoon and that all the attackers had been killed.

The Taliban claimed responsibility for the attack, saying five people took part, while a witness told Reuters he saw four attackers dressed in army uniforms. The AP reports that Danish said in a news conference that preliminary investigations reveal that six insurgents made their way into the hotel.

A wedding party was taking place in one part of the hotel while several dozen guests were there for a conference, Jennifer Glasse reports for NPR from Kabul.

Footage from outside the building showed fire and black smoke emanating from the hotel's top floor, while at least one person uses a bedsheet to rappel from one balcony to the one below.

The U.S. Embassy in Kabul had put out an alert on Thursday saying it was "aware of reports that extremist groups may be planning an attack against hotels in Kabul," though specifically mentioned a different hotel.

"This attack shows how unpredictable the security situation remains here," Glasse says.

The hotel was "heavily protected like most public buildings in Kabul," but the gunmen managed to enter the hotel's main area through a kitchen, hotel manager Ahmad Haris Nayab told Reuters.

Taliban fighters previously attacked the Intercontinental Hotel in 2011, according to the news service.

Less than a month ago, a suicide bombing in Kabul killed 41 people, while a truck bombing in May killed more than 150.

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