“It is definitely one of the worst crashes you ever seen !! At least five people were killed Friday afternoon in a wreck after a truck crossed onto the other side of the freeway, crashing head on with multiple vehicles east of Los Angeles, according to the California Highway Patrol.Details regarding other possible injuries were not immediately available. Both sides of the 10 Freeway near Riverside Avenue are expected to remain closed for hours. Aerial video showed a mangled guardrail dividing the east and westbound freeway lanes.A concrete pumping truck traveling west in the third lane on the 10 Freeway crossed over onto eastbound lanes, taking out a guardrail and crashing head on with multiple vehicles. Several of the vehicles were fully engulfed in flames, and some were underneath the truck. It wasn’t immediately clear what caused the driver crossed onto the eastbound side.Traffic was backed up to the city of Ontario on the eastbound side, and to California Street on the westbound side. The eastbound side would be shut down for at least 10-12 hours, while the worked to reopen the westbound side sooner. “It is definitely one of the worst crashes I have responded to in my nine-year career,” said Officer Ryan Alvarez.