A suicide bomber killed at least 27 Shi’ite militiamen outside the Iraqi town of Jurf al-Sakhar on Monday after security forces pushed Islamic State militants out of the area over the weekend, army and police sources said.

The attacker, driving a Humvee vehicle packed with explosives and likely stolen from defeated government troops, also wounded 60 Shi’ite Muslim militiamen, who had helped government forces retake the town just south of the capital.

Iraqis are bracing for more sectarian attacks on Shi’ites, who are preparing for the religious festival of Ashura, an event that defines Shi’ism and its rift with Sunni Islam.