A roller coaster derailed Monday at the Six Flags Magic Mountain amusement park, slightly injuring four people and leaving about two dozen stranded about 20 feet in the air, authorities said.
The Ninja coaster struck a tree branch shortly before 6 p.m. and stopped, said Michael Pittman, a Los Angeles County Fire Department dispatch supervisor.
Televised news reports showed at least one of the cars that normally are suspended beneath a track dangling at an angle, derailed at the front.
Pittman said four people on the ride received minor injuries, but they and other riders remained on the stalled coaster, stranded 20 to 30 feet in the air, more than an hour after the accident.
Firefighters had ladders available to rescue them if necessary, he added.
The Ninja coaster can hold up to 28 riders.
"As you shoot down the snake-like steel track you'll grip the hillsides and blast through the trees swiftly, slicing through the landscape. Ninja pivots with precision as you narrowly miss tagging land and water, whipping around at 55 miles per hour,'' according to the amusement park's website.
Six Flags Magic Mountain is in the Valencia area of Santa Clarita, about 25 miles north of Los Angeles.