Soldier Killed in Iraq Raid Belonged to Delta Force It was the first American combat death in Iraq since 2011, officials said.

 -- The U.S. Army soldier killed in the raid that freed 70 hostages from an ISIS prison in northern Iraq was a highly-decorated, veteran member of the elite Delta Force, U.S. military sources told ABC News.

Master Sergeant Joshua L. Wheeler is the first American combat death in Iraq since American troops returned in mid-2014 to train, advise and assist the Iraqi military to fight ISIS, military officials said.

Wheeler, 39, of Roland, Oklahoma, "died Oct. 22, in Kirkuk Province, Iraq, from wounds received by enemy small-arms fire during an operation," the Defense Department said in a statement, which also noted that he was assigned to "Headquarters U.S. Army Special Operations Command, Fort Bragg, North Carolina." He is survived by his wife and four sons, the Army said.

Two military officials have told ABC News that Wheeler was a team leader for the elite Army special operations unit commonly known as "Delta Force," which is based at that command at Fort Bragg.

Wheeler was one of 30 American special operations forces personnel who served as advisers to a similar sized force of Kurdish Peshmerga forces that were leading the raid on a compound outside of Hawlijah, where it was believed ISIS was holding 20 Kurdish hostages, officials said. The Kurdish government believed that the hostages were facing imminent execution at the hands of their captors. That information was corroborated by U.S. intelligence that spotted as many as four mass graves at the compound, officials said.

According to biographical information for Wheeler released by Army Special Operations Command, Wheeler joined the Army at 19 and was just a month short of turning 40 when he died -- a long, 20-plus-year career in combat. In the course of that career, Wheeler earned a stunning 11 Bronze Stars, including four with the "Valor Device" for particular acts of heroism.

He served as a U.S. Army Ranger and then joined U.S. Army Special Operations Command in 2004, after which he deployed 11 times in support of combat operations in Iraq and Afghanistan, the Army said. Those deployments would have been as part of Delta Force, according to U.S. military sources.

At a Pentagon briefing today, Defense Secretary Ash Carter praised Wheeler's heroism, noting he played a pivotal role in the mission's success.

“The plan was not for the U.S. advise-and-assist and accompanying forces to enter the compound or be involved in the firefight," Carter said. But when a firefight ensued, Wheeler "ran to the sound of the guns, and he stood up, and all the indications are it was his actions and that of one of his teammates that protected those who were involved in breaching the compound and made the mission successful," Carter said.

“It wasn't part of the plan, but it was something that he did. And I'm immensely proud that he did that,” he said.

Carter also said he expects more raids in the future, noting the success in rescuing hostages and the significant intelligence on ISIS recovered as part of the mission.

“This is the stuff you get and the great value, by the way, of raids of this kind. And I expect that we'll do more of this kind of thing," Carter said.

Conducting additional raids would not mean the U.S. was now assuming a combat role in Iraq, Carter added, noting: "It represents a continuation of our advise-and-assist mission."

"When we find opportunities to do things that will effectively prosecute the campaign, we're going to do that," he said. "I suspect that we'll have further opportunities in the future, and we would want to avail ourselves of them."

The Kurdish and U.S. special operations teams were transported to the prison site aboard Blackhawk and Chinook helicopters, officials said.

According to Col. Steve Warren, the U.S. military spokesman in Baghdad, the U.S. team members were serving as advisers to the mission and following rules that called for them to stay behind the last concealed position.

They joined the fight after the Kurdish forces sustained what Warren called "withering fire." Wheeler was killed in the intense firefight that ensued, Warren said.

Afterwards, the U.S. and Kurdish forces discovered that the ISIS prison actually held more than 70 hostages, all of them Sunni Arabs, officials said. They included 22 members of the Iraqi security forces and the rest were Iraqi civilians.

"It is always a tragedy when we lose one of our own," Warren said. "In the end, we saved 70 people from execution that was planned in a few hours."

Carter is scheduled to be at Dover Air Force Base in Delaware on Saturday when Wheeler's remains are returned to the U.S.