Los Angeles (CNN) -- A tour bus crash with a big rig and two vehicles in California early Wednesday killed four people and injured nearly two dozen others near the Arizona border, according to the California Highway Patrol.
All four fatalities were passengers on the tour bus, which was carrying 25 people, CNN affiliate KCBS-TV said.
A truck carrying metal pipes jackknifed around 2 a.m. Wednesday on Interstate 10 near Blythe, sending the load across the highway and apparently into the opposite lane of traffic, where the tour bus was traveling, the station reported.
"The pipes subsequently caused some of the vehicles to crash into them in the eastbound lanes and it appears they could have rolled into westbound traffic which is where the bus was traveling," Terri Kasinga of Caltrans told the TV station.
The bus struck the pipes and then ran off the freeway by 40 to 50 feet, KCBS reported. It then fell down an embankment and landed on its side, the station said.
No further details were available on the two vehicles involved in the crash.
The tour bus was traveling westbound on I-10 from El Paso, Texas, to Los Angeles and had just made a stop in Phoenix, the highway patrol told the affiliate.
It was not immediately known which company operated the bus.