BAGHDAD, March 24, SPA -- A roadside bomb killed four U.S. soldiers in Baghdad on Sunday, the military said, pushing theOverall American death toll in the five-year war to atLeast 4,000. The grim milestone came on a day when at least61 people were killed across the country, the Associated Press reported. Rockets and mortars pounded the U.S.-protected Green Zone,underscoring the fragile security situation and theresilience of extremist groups despite an overall lull in violence. The soldiers with Multi-National Division _ Baghdad wereon a patrol when their vehicle was struck at about 10 p.m. in southern Baghdad, the military said. Another soldier waswounded in the attack. Identities of those killed were withheld pendingnotification of relatives.--SPA www.spa.gov.sa/539297