BAGHDAD, March 7 (Reuters) - Insurgents with guns and a roadside bomb ambushed Shi'ite Muslim pilgrims heading for a religious festival in southern Baghdad on Wednesday, killing five and wounding 10, a police source said. The attack in the Doura area of the Iraqi capital occurred after nearly 150 pilgrims were killed in a string of attacks on Tuesday. A double suicide bombing south of Baghdad killed 115 pilgrims in a busy street. The attacks on pilgrims occurred just over a year after the bombing of a Shi'ite shrine in the city of Samarra that sparked an upsurge in sectarian violence in Iraq. Crowds of pilgrims were out on the streets of Baghdad on Wednesday, undaunted by Tuesday's attacks.