Iraqi police arrested four would-be homicide bombers in this southern Iraqi city Tuesday, hours after 143 people were killed in near simultaneous and coordinated attacks on Shiite shrines elsewhere.

Police sources told The Associated Press that two men -- a Syrian and an Iraqi -- were arrested after a car bomb was found outside the Seyed Ali al-Musawi Mosque in central Basra.

Tens of thousands of worshippers were in the area when the bombers were discovered just after 12 p.m.

Later in the day, in the al-Maqal neighborhood of Basra, police arrested two women who were wearing explosives-laden belts as the marched in a procession to mark Ashoura.