Roadside bombs killed four US soldiers in the Baghdad area, including three in a single strike, the military said Tuesday. Three Task Force Marne soldiers were killed Saturday when a roadside bomb struck their convoy south of Baghdad, according to a brief statement that provide no more details. One Multi-National Division - Baghdad soldier was killed and another wounded Monday when their vehicle was targeted by an armor-piercing explosively formed penetrator, or EFP, in a western section of the capital, the military said separately. The US military has accused Iran of supplying Shi'ite extremists with EFPs to step up attacks against American forces. Teheran denies the allegations. The deaths raised to at least 3,678 members of the US military have died since the Iraq war started in March 2003, according to an Associated Press count.