An explosion at an ammunition warehouse injured 13 people in southern Baghdad on Monday, The National news website reports.

The blast took place in a munitions storage run by Iraq’s powerful Popular Mobilization Forces, an umbrella group of militias mainly aligned with Iran, according to the report.

The explosion occurred about 7:00 p.m. local time in the Abu Dshir area, south of Baghdad.

Videos showed massive clouds of smoke over the area, with several blasts heard.

The Iraqi Health Ministry said that the injured victims were transferred to local hospitals for treatment.

It is unclear who was responsible for the attack, but last month an unmanned drone dropped explosives on a base belonging to the Popular Mobilization Forces in northern Iraq.

At the time, Iraqi security officials claimed that one fighter had been killed in the attack, and two Iranians injured.

Subsequent, unconfirmed reports claimed that Israel was behind that attack. Israel has not commented on the reports.