BAGHDAD — Four members of Iraq’s military were wounded Sunday in a rocket attack targeting an air base just north of Baghdad where American trainers were present until recently, Iraqi security officials said.

The attack by at least six rockets came just days after Iran fired ballistic missiles at two bases in Iraq that house U.S. forces, causing no casualties.

There are no Americans currently at Balad air base and there were none during the attack, according to a coalition spokesman. The base had hosted American trainers, advisers and a company that provides maintenance services for F-16 aircraft, according to an Iraqi defense official.

Recent heightened tensions between the U.S. and Iran were sparked last month when a rocket attack killed an American contractor at a base in Iraq. The U.S. has blamed that attack and others on Iran-backed militias.

U.S. Secretary of State Mike Pompeo said in a tweet Sunday that he was “outraged” by the attacks.

Sunday’s attack wounded an Iraqi air force officer and three enlisted men, Iraqi security officials said.

Some rockets fell on a restaurant inside the air base, the officials said.

No group claimed responsibility for the attack.

The base is located some 50 miles north of Baghdad.