CAIRO (AP) — Three American fighter jets were mistakenly downed by friendly Kuwaiti fire Monday during an Iranian air assault, the U.S. military said.

All six crew members safely ejected from the F-15E Strike Eagles and were in stable condition after being recovered, the U.S. said.

An attack by Iranian aircraft, missiles and drones was underway at the time the planes were shot down.

Iranian state television claimed that Iran had targeted one of the U.S. planes that crashed in Kuwait without elaborating.

Explosions could be heard as one of the planes fell from the sky in flames, said witness Ahmed al-Asar, who rushed to the scene with about a dozen others as an airman parachuted to the ground.

Al-Asar initially thought it was an Iranian pilot, but recognized he was American before rescuers whisked him away.

Kuwait said its air defenses had accidentally shot down the jets as part of its support for the U.S. combat operation in Iran, U.S. Central Command said.

“The U.S. Air Force fighter jets were mistakenly shot down by Kuwaiti air defenses,” the military said. “Kuwait has acknowledged this incident, and we are grateful for the efforts of the Kuwaiti defense forces and their support in this ongoing operation.”

The cause of the incident was under investigation, the U.S. said.

A total of four U.S. servicemembers have died since the conflict started over the weekend.