Three gunmen armed with pistols, AK-47 rifles and hand grenades stormed a government building in the Iraqi Kurdish capital Erbil on Monday.
The men approached the building shortly before 8am and opened fire, Erbil deputy governor Tahir Abdullah said. One government employee was killed and two policemen wounded in four hours of clashes.
Snipers took up positions on a nearby building in Erbil's busy commercial district and opened fire at the militants. Kurdish security forces entered the building through the ground floor, killing the gunmen, who had taken hostages.
"We believe that the attackers are ISIS because of the tactics they used in breaking into the building from the main gate," said a security official.
"At around 7:45am, two gunmen approached the entrance of the governorate and opened fire at the guards. They managed to enter and now they are on the third floor," deputy governor Tahir Abdullah said.
A spokesman for the KRG said: "The gunmen seized weapons from the guards. The men were shouting "Allahu akbar".
Security forces killed two gunmen, while some attackers had remained with hostages. It was not clear how many gunmen were inside the building.
There were conflicting accounts on the details of the attack. Security officials said two of the men carried out suicide bombings. But Erbil Governor Nawzad Hadi said none of the men blew themselves up.
Security forces have cleared the streets around the building in the busy city centre. These types of attacks are rare in Erbil, one of the most stable cities in Iraq.
Mr Abdullah told Kurdish news agency Rudaw that security forces had entered the building.
“I’d like to reassure everyone that the situation is under control as security forces have entered the building and are searching for the attackers room by room,” he said.
ISIS, which has been largely defeated in Iraq, has carried out bombings in Erbil in the past. The group has targeted Kurdish forces and civilians in recent years. They have also in the past established units composed solely of Kurdish militants who fought in both Iraq and Syria.