Story highlights ISIS has previously coordinated attacks on energy facilities in the oil-rich region

Earlier, gunmen attacked a nearby gas facility owned by same company, killing 4

(CNN) An ISIS hostage-taking at an oil field near the northern Iraqi city of Kirkuk has ended with the attackers killed and their captives safely freed, a senior security source in the city told CNN.

Four hostages -- employees of the Iraqi North Oil Company -- were taken captive after four attackers, believed to be wearing suicide vests, stormed the Bai Hassan oil field northwest of Kirkuk on Sunday, the source said.

One of the attackers blew himself up when security forces responded. The other attackers were later killed by security forces.

The ISIS-affiliated Amaq news agency released a statement claiming responsibility for the attack, which was widely circulated by the terror group's supporters on social media networks.

The standoff was the second armed attack on an energy facility in the Kirkuk region Sunday, following an earlier deadly attack on a nearby gas compression facility owned by the same company.

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