It was the most deadly attack to hit U.S.-led forces in almost a year in Iraq, where tensions have escalated between U.S. forces, their Iraqi and Kurdish allies on one side and Iran-aligned militias on the other.
A coalition spokesman said on Twitter the attack hit coalition forces in the Kurdish regional capital of Erbil, and that more details would follow.
Kurdish security sources said at least three rockets landed near Erbil International Airport in the autonomous region late at night. Reuters reporters heard several loud explosions and saw a fire break out near the airport.
U.S. troops occupy a military base adjacent to the civilian airport.
A statement from the Kurdish interior ministry said a number of rockets were fired towards Erbil and its outskirts around 9:30 p.m. local time and some people were wounded, but it offered no further details.
A group calling itself Saraya Awliya al-Dam claimed responsibility for the attack on the U.S.-led base, saying it targeted the “American occupation” in Iraq. It provided no evidence for its claim.
U.S. Secretary of State Antony Blinken said late Monday the United States was “outraged” by the attack.
In a statement, Blinken said he had reached out to Kurdistan Regional Government Prime Minister Masrour Barzani “to discuss the incident and to pledge our support for all efforts to investigate and hold accountable those responsible.”
Groups that some Iraqi officials say have links with Iran have claimed a series of rocket and roadside bomb attacks against coalition forces, contractors working for the coalition and U.S. installations - including the embassy in Baghdad - in recent months.