The California Highway Patrol now says five people died when a tractor-trailer truck plowed through a center divider, rammed head-on into traffic and burst into flames on a freeway east of Los Angeles. Authorities say a cement pumping truck was heading west on Interstate 10 in Rialto shortly before 1 p.m. Friday when it smashed through the guard rail into eastbound traffic. CHP officials say the truck and at least three other vehicles caught fire. The half-dozen vehicles involved in the wreck also included cars, a trash-hauling truck and a motorcycle. TV reports showed the big-rig sprawled on its side and the wreckage of two burned-out cars next to the scorched trash-hauler. It’s unclear whether speed or alcohol may have contributed to the accident. The freeway is closed in both directions and traffic is backed up for miles. Police say a tractor-trailer plowed through the center divider of a Southern California freeway and rammed head-on into traffic. At least four people were killed in the fiery crash. California Highway Patrol Officer Brian Alvarez says a drilling or cement pumping truck was heading west on Interstate 10 in Rialto when it plowed into oncoming traffic. At least four other cars and trucks were involved in the resulting crash. The cause of the crash is under investigation. The freeway has been closed and traffic was backed up for miles. Alvarez says the route will remain closed until late Friday night.