One member of a U.S. special operations team was killed during an operation to rescue hostages held by Islamic State militants in northern Iraq, the first American killed in ground combat with the militant group, U.S. officials said on Thursday.

Hostages were successfully rescued during the operation, a U.S. official told Reuters. CNN said about 70 Kurdish hostages were freed.

A U.S. official confirmed to Reuters that one American was killed. No further information was available on the mission, which local residents and a Kurdish military commander said was carried out in the Hawija area in northern Iraq.

It was the first U.S. serviceman killed in ground combat operations against Islamic State, which has been the target of daily air strikes in Iraq and Syria by a U.S.-led coalition for more than a year.

One source in the Hawija area said the operation involved helicopters and targeted a makeshift prison where Islamic State was holding a number of hostages.

NBC News, citing unidentified sources, said the operation was requested by the Iraqi government and those rescued were Kurdish fighters. It said the U.S. forces suffered casualties but the number of injuries was unclear.

Another Reuters source in the Hawija area said the special forces raided a house where Islamic State commanders were gathering, triggering gun battles and blasts that lasted several hours.

Sheikh Jaafar Mustafa, a senior commander of the Kurdish peshmerga forces, confirmed an operation had taken place but said he had no further information about it. In May, American special operations forces killed senior Islamic State leader Abu Sayyaf from Tunisia in a raid in Syria.

Hawija is a stronghold of Islamic State militants who have captured Kurdish peshmerga fighters in battles.

(Reporting by Phil Stewart in Washington and Isabel Coles in Erbil; Writing by Mohammad Zargham in Washington; Editing by Doina Chiacu)