An American Marine was killed and others seriously injured Saturday when a rocket fired by ISIS landed near his position in the town of Makhmur, 75 miles southeast of Mosul, a U.S. defense official told Fox News.
The official did not want to give the exact number of wounded but said the number is less than five. They were flown to a hospital away from the base, the official said.
"It was a lucky strike by ISIS," the official said..
The Pentagon is expected to make an announcement shortly.
The US-led coalition fighting ISIS released a statement about the attack Saturday morning, but the nationality of the soldier was withheld. It said the soldier was killed by "enemy action," but was not more specific.
The soldier is the second American killed fighting ISIS since combat operations began in August 2014.
In October, a Delta Force master sergeant was killed during a daring hostage rescue in Iraq.
The death of Army Master Sgt Joshua Wheeler was the first American casualty in Iraq since the withdrawal of US forces in 2011.
There are roughly 3,700 US troops on the ground in Iraq advising the Iraqi Army. Earlier this month, a brigade from the 101st Airborne Division relieved a similar sized brigade from the 82nd Airborne Division.
In December, Defense Secretary Ash Carter announced the deployment of a 200-man special operations task force to Northern Iraq to begin kill/capture missions against the Islamic State.
Last month, the assault force captured alive a mid-level ISIS operative tied to the group's chemical weapons program.
After weeks of interrogation he was turned over to Iraqi forces. A US military spokesman said the US would still have access to question him further should the need arise.
It was the second time in the past year US special operations forces have captured an ISIS operative from the battlefield.
In May, a Delta Force team killed Abu Sayyaf and captured his wife Umm Sayyaf during a nighttime raid in Syria.
The Justice Department recently charged Mrs. Sayyaf with conspiracy to kill a 26-year old American aide worker Kayla Mueller, who was held captive by the Sayyafs and later became a sex slave for ISIS emir, Abu Bakr al-Baghdadi.