A U.S. soldier was killed and 70 Kurdish hostages were freed in an operation carried out in Northern Iraq on Thursday, an unidentified U.S. official has reportedly said.

This would be the first U.S. combat fatality on the ground in the fight against ISIS in Iraq and Syria, CNN said.

One official, who spoke on condition of anonymity because the operation had not yet been made public, said the U.S-led rescue effort was carried out overnight in the vicinity of Hawija, an ISIS stronghold west of Kirkuk.

The circumstances in which one U.S. military member was killed were unclear, but one U.S. official said the soldier was killed in a firefight at the scene.

The relative of one of the Kurdish hostages said he's been informed of their rescue in a U.S.-led raid.

Irfan Sadradeen, the uncle of Kurdish peshmerga fighter Meriwan Mawlud, said he was contacted by a peshmerga official who informed him about the raid on the ISIS near Hawija. Irfan said he was told that paratroopers landed at a poultry farm, close to the home of the main sharia judge of Hawija, where they launched their rescue.

"We are waiting for more information. A peshmerga official called us today confirming the news of the raid," he said, adding that he was told 15 ISIS fighters were killed in the raid. "None of them arrived to this area yet but we are waiting for them," he said.

Coalition officials in Iraq declined to comment when contacted by The Associated Press.