This is a Transportation Alternatives sponsored mural in the Gowanus area, on Butler Street and 3rd Ave. The painting depicts 3 children who have been killed by cars and trucks along 3rd Avenue. According to the Gowanus Lounge, "[t]he project was inspired by the tragic death of James Rice--who was struck and killed by a Hummer at Third Avenue and Baltic Street on his way home from pre-school in February--and many other children that have been injured and killed by cars."
More information about the mural is available at the Groundswell Mural Project.