Security forces stormed the facility and regained control freeing 15 employees. It is not clear if the four attackers died or they fled
Militants stormed a gas facility in northern Iraq today, killing four workers and planting several explosives before security forces managed to regain control, security sources said.
At least four gunmen with hand grenades broke through the external door of the AB2 gas compressor station, about 15 km (10 miles) northwest of Kirkuk, at around 0300 (1200 GMT), leaving two guards in critical condition.
They proceeded to shoot dead four employees in a control room inside and planted explosives charges, at least five of which went off, the sources said.
Forces from the elite counter-terrorism service then stormed the facility, regaining complete control and freeing 15 other employees who had hidden in a separate room. It was not yet clear if the attackers had been killed or if they had fled.
There was no immediate claim of responsibility for the attack, but Islamic State has previously targeted oil facilities in the area with explosives, repeatedly targeting oil wells at Khabbaz oilfield southwest of Kirkuk.
Islamic State militants, who seized a third of the Organization of the Petroleum Exporting Countries (OPEC) producer's territory in 2014, have since been pushed back in many areas by an array of Iraqi forces backed by US-led coalition airstrikes.