At least 13 people, including the commander of Iran’s Revolutionary Guards, were killed in an airstrike in eastern Syria.

The Syrian Observatory for Human Rights said the attack took place on Tuesday (March 26).

The monitoring group said nine pro-Iranian fighters, including a Revolutionary Guard commander, were killed in the airstrikes.

It also said four more people were killed in a separate attack in the Iraqi border town of Albu Kamal.

However, the British-based organization could not say who carried out this attack. Moreover, no one immediately claimed responsibility for the attack.

Israel has carried out hundreds of strikes targeting pro-Iranian groups fighting alongside President Bashar Assad’s forces in the country’s more than decade-long civil war.

The United States has carried out a relatively small number of strikes against pro-Iranian groups in eastern Syria. However, the media close to the Syrian government say that the latest attack was American.