At least three people were killed after explosions at a base of the Iran-backed Iraqi paramilitary group Hashd al-Shaabi (Popular Mobilization Forces – PMF) in Iraq's capital Baghdad on Tuesday.

A PMF official said three members of the paramilitary group were killed and four others are critically wounded.

"Blasts occurred in a base belonging to the Hashd al-Shaabi" in Babylon province, a security source said, referring to an alliance of pro-Iranian former paramilitary groups now integrated into the regular army.

"The cause of the blasts was not immediately known," the source added, but a PMF official said an "airstrike" hit the base.

On July 18, an explosion hit "logistics" warehouses belonging to PMF south of Baghdad, and in April, one person was killed and eight wounded in a blast at a military base housing PMF groups in Babylon province.

PMF is an integral part of the Iraqi security apparatus under the authority of the prime minister.

It includes some pro-Iran groups that have carried out dozens of attacks against U.S. forces in Iraq and neighboring Syria.