During an overnight raid in Eastern Syria, U.S. Special Operations forces managed to kill a key ISIS commander.

As reported by CNN, U.S. Defense Secretary Ash Carter said via statement that the ISIS commander, identified by the assumed name Abu Sayyaf, was killed in an intense firefight after he resisted capture in the raid, which took place at al-Omar.

Special Operations forces also took into custody his wife and freed an 18-year-old Yazidi woman who, according to the Pentagon, had been held as a slave.

The ground operation was led by the Army's Delta Force, and there were about two dozen members of Delta Force involved in the raid. Speaking to CNN, A U.S. official who had some familiarity with the operation said Delta Force entered the target area on Blackhawk helicopters and V-22 aircraft.

Bernadette Meehan, the National Security Council spokeswoman, said as soon as the United States was confident that the situation was right for the operation to succeed, Obama had authorized the raid "upon the unanimous recommendation of his national security team."

"Abu Sayyaf was a senior ISIL leader who, among other things, had a senior role in overseeing ISIL's illicit oil and gas operations -- a key source of revenue that enables the terrorist organization to carry out their brutal tactics and oppress thousands of innocent civilians," Meehan said via statement.

ISIL is another name for the Islamic State, which is also known worldwide as ISIS.

The spokeswoman noted that Abu Sayyaf was known to be involved with the group's military operations.

"The U.S. government did not coordinate with the Syrian regime, nor did we advise them in advance of this operation," Meehan said, according to The New York Times. “We have warned the Assad regime not to interfere with our ongoing efforts.”