Updated at 4:11 p.m. ET
IRWINDALE, Calif. A charter bus went through a chain-link fence Thursday off the side of Interstate 210 and ended up on its side down a dirt embankment between the freeway and railroad tracks in Irwindale.
More than 50 people received minor injuries, including nine that were taken to hospitals for evaluation or treatment, said Cheryl Sims, a dispatch supervisor with the county Fire Department. Tallies at the scene ranged between 52 and 55 and the discrepancy could not be immediately resolved.
The bus was carrying gamblers to an Indian casino. It went off the side of the road around 10 a.m. local time and ended up on its side in dirt along nearby railroad tracks.
Ambulances and helicopters converged on the freeway in eastern Los Angeles County and firefighters laid out red, yellow and green tarps to evaluate the injured.
At least five were flown by helicopters to trauma centers, fire Supervisor Ed Jacobs said.
TV news reports showed several people strapped to gurneys and being carried away.
The white bus, its front window knocked out, lay on its right side. Long skid marks led across three freeway lanes toward the bus. Weather was clear and dry.
Some of the passengers were able to get out on their own, while others needed to be rescued by firefighters, said Los Angeles County Fire Capt. Brian Jordan. Bystanders also aided in the rescue, Jordan said.
Fire officials said most of the passengers were senior citizens and many did not speak English. Cantonese and Mandarin translators were requested to help communicate with bus passengers.
The freeway was shut down in both directions for at least 30 minutes as victims were transported.
Witness Brent Montague told KNX 1070 NEWSRADIO he saw the accident and said the bus appeared to be trying to merge from one side of the freeway to the other when it swerved to avoid a car.
"The tires locked up and then they swerved left again, and then it swerved right, and it looked like he was gonna get on the shoulder okay, but then he over-corrected and then it went over on its faster side into the dirt," Montague said.
CBS Los Angeles confirms the tour bus is owned by Da Zhen, a luxury motor coach transportation service based in Monterey Park.
Da Zhen received a "satisfactory" rating during its last major review by federal inspectors, in 2010, according to U.S. Department of Transportation records.
Those records report that in the past two years, the company had no crashes among its nine buses. Two of its buses were cited for speeding in Arizona in February, while another was cited for "following too close" in May in Nevada.
Overall, the buses performed relatively well in mechanical inspections, failing just two of 30 over the past two years, according to the records. That 7 percent rate was significantly below the national average.
The route is commonly used for "gamblers' specials" that take tourists to desert casinos and Las Vegas.
It was unknown what caused the collision, but California Highway Patrol Officer Saul Gomez says the bus will be held for evidence. No other details were immediately available.