The Pentagon confirmed Thursday that one U.S. service member was fatally wounded earlier in the day during an Iraq mission to rescue about 70 hostages from the Islamic State in Iraq and Syria, the first U.S. combat death against the group.

"On behalf of the men and women of the Department of Defense, we offer our sincere condolences to the family of the U.S. service member who was killed in this operation," said Pentagon press secretary Peter Cook.

So far, there have been nine previous U.S. deaths as part of Operation Inherent Resolve against ISIS, also known as ISIL, but all of them in non-hostile situations. The president has said there would be no ground troops fighting in Iraq; he has sent about 3,500 U.S. troops to act as advisers and trainers for the Iraqi security force.

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"The U.S. and our coalition will continue to work with our Iraqi partners to degrade and defeat ISIL, and return Iraq to the full control of its people," he said.

The service member, who won't be identified until 24 hours after next of kin is notified, was wounded and died after receiving medical care, according to Cook.

The mission, carried out by U.S. Special Operations Forces, was in support of an Iraqi Peshmerga operation to rescue the hostages at an ISIS prison near Hawijah. Four Peshmerga soldiers were wounded in the mission.

"This operation was deliberately planned and launched after receiving information that the hostages faced imminent mass execution," Cook said.

Approximately 70 hostages were rescued, including more than 20 members of the Iraqi Security Forces, Cook said. Five ISIS terrorists were detained by the Iraqis and "a number" were killed as well. In addition, the U.S. recovered important intelligence about ISIS, Cook said.

He said the U.S. helicopters provided the air support for the operation, and U.S. forces accompanied Iraqi Peshmerga forces to the compound.

Cook also said the mission was authorized consistent with counter-ISIS efforts to train, advise and assist Iraqi forces.