Inside the ISIS hostage rescue that left a U.S. soldier dead

The first American was killed in combat Thursday in the war against the Islamic State of Iraq and Syria (ISIS). The soldier died during a daring raid in northern Iraq to free dozens of prisoners who were about to be executed by the Islamic terror group.

The predawn raid involved 30 U.S. Special Operations Forces, including Delta Force commandos and Kurdish fighters.

U.S. soldier killed during rescue mission in Iraq

The American forces were there to advise and assist, not to be an assault force -- but that role changed when the U.S. troops saw the Kurdish Peshmerga get pinned down in a heavy exchange of fire with ISIS fighters.

"That call was made on the ground," said a US defense official.

It was a consequential one, with a U.S. serviceman fatally wounded in the gunfire. While his name and branch of service has not been made public due to Pentagon protocol, officials described him as an experienced operator.

It was the first time that Kurdish Peshmerga forces asked for U.S. assistance in a hostage rescue. While they suspected that ISIS had imprisoned some of their fellow Kurds at the prison complex, the commandos were surprised to find that the vast majority of the hostages were Sunni Arab civilians from the local town along with 20 Iraqi security forces.

They also discovered that ISIS held some of their own fighters hostage, accused of being spies and scheduled for execution.

Flash Points: Unusual circumstances surround Iraq hostage raid

The raid raised questions about President Obama's vow not to put U.S. soldiers into combat in Iraq. But Pentagon Spokesperson Peter Cook said the Special Operations forces were only assisting the Kurdish fighters.

"In that support role, they are allowed to defend themselves and also defend partner forces and to protect against the loss of innocent life," Cook said.

When asked whether the raid justified the loss of an American life, defense officials said that they did save the lives of the hostages and also collected valuable intelligence.

The rescue was launched after U.S. intelligence saw evidence of mass graves being dug inside the walls of the prison compound. Some of the freed hostages told U.S. officials ISIS had told them they would all be killed after their morning prayers.

  • Margaret Brennan

    Margaret Brennan is moderator of CBS News' "Face The Nation" and CBS News' senior foreign affairs correspondent based in Washington, D.C.