Violence left nearly 50 people dead in two major southern cities when members of a shadowy, messianic cult attacked police and fellow Shiite worshippers - a year after a similar plot was foiled during Shiite Islam's most important holiday. Iraqi authorities said at least 36 people were reported killed in Basra, Iraq's second largest city, and at least 10 in Nasiriyah, where witnesses said US-led coalition jet fighters and helicopter gunships on Friday targeted a police station seized by cult gunmen. US military spokesman Maj. Brad Leighton said jet fighters flew over the area in a show of force after the Iraqi's requested help, but no airstrikes were carried out. Some clashes raged into the night, raising the possibility of more casualties. The assaults were launched as hundreds of thousands of Shiites observed the Ashoura holiday by marching, singing and beating their chests to honor the martyrdom of their most beloved saint. Followers of the cult - the Soldiers of Heaven - seek to speed the return of another Shiite figure known as a "Hidden Imam," who believers say will bring justice to the world.