At least 18 people were killed and 50 others injured after a group of gunmen launched an attack on a mall in Baghdad Monday evening, Iraqi officials said.

The incident began Monday evening after a group of gunmen detonated a car bomb outside of Baghdad's Jawaher mall, reported Reuters. Shortly afterward, the group clashed with nearby security forces then stormed the mall, taking between 50 and 75 people hostage.

Officials reporting the situation revealed the attackers had complete control of the mall for awhile.

"They completely control the mall right now, they have men on the roof," the official said.

"They are inside the Zahrat Baghdad mall. When the security forces got too close, they killed three hostages," he added, according to AFP. "We are taking a cautious approach now. We want this attack to end with the lowest possible number of casualties."

A counter-terrorism force was deployed to the scene, and snipers were set up on buildings around the mall. Though it's not clear how security forces managed to secure the mall, all the attackers were believed to be either dead or arrested by the end of the one-and-a-half-hour incident.

In the aftermath of the attack, the highly fortified Green Zone, which had been reopened to the public in October, was shut down, along with a number of major roads, shopping malls and bridges due to fear of a follow-up attack, according to FOX News.

It was initially unclear who is responsible for the attack, with the only clue being testimony from a police source who described the gunmen as "wearing Daesh-style clothes." However Daesh, more commonly known as ISIS, later claimed responsibility for the attack, according to the Associated Press.

If true, this incident would mark a rare instance of ISIS taking hostages at the site of an attack ever since they took control of large parts of Iraq in 2014.