A 5-year-old boy and two women were killed, while three other children and a man were in serious condition after a collision between a passenger car, a van and a large tractor-trailer rig in the Valencia area of the Santa Clarita Valley. The California Highway Patrol said the truck crashed broadside into the automobile, pushing it into the van, on Henry Mayo Drive, five miles west of Six Flags Magic Mountain. The two dead women were in the front seat of the automobile and the dead boy was in the back seat, authorities said. Also in the back seat were a 7-year-old boy and an infant girl, who were reported in critical condition at Henry Mayo Newhall Memorial Hospital, and a 3-year-old girl who appeared to have only minor injuries. The man driving the van was reported in serious but stable condition at Holy Cross Hospital in Mission Hills, and the driver of the truck appeared to be unhurt, according to Los Angeles County Fire Capt. Roy Burleson.