Iraq's Popular Mobilization Forces, an official security force, said its command post at Kalso military base about 50 km (30 miles) south of Baghdad was hit by a huge explosion late on Friday, and two security sources said it resulted from an air strike.
"The blast has caused material damage and injuries," PMF said in a statement, adding that a team was investigating.
The two security sources said it was not known who was responsible for the air strike. A U.S. official said there had been no U.S. military activity in Iraq.
Three PMF fighters were wounded, according to Muhannad Najim, an official with the city of Hilla's local government.
Israel carried out an attack on Iranian territory on Friday, sources said, days after Iran struck Israel with a barrage of drones and missiles.
The PMF started out as a grouping of armed factions, many close to Iran, that was later recognized as a formal security force by Iraqi authorities.
Factions within the PMF took part in months of rocket and drone attacks on U.S. forces in Iraq amid Israel’s Gaza campaign but halted attacks since early February.
