A new roller coaster stalled 150 feet above the ground Sunday afternoon, stranding a dozen riders for almost two hours at a Northern California amusement park, according to local reports.

Twelve passengers on the Superman Ultimate Flight roller coaster at Six Flags Discovery Kingdom in Vallejo, Calif., became stranded atop the park’s newest ride when it stopped at its crest around 2:30 p.m., Six Flags spokeswoman Nancy Chan told the Vallejo Times-Herald.

Vallejo fire rescue crews were dispatched to the scene at about 3 p.m. after receiving an emergency call.

Park engineers prepared a large crane equipped with a big personnel bucket to reach the riders, and firefighters took up water and sunblock.

Park officials said crews had trained for this type of mission.

“We arrived; we put the crane that’s on site into place,” Vallejo Fire Department Batt. Chief Raymond Jackson said. “We’ve actually done some training in this in case this situation arose.”

Jackson said firefighters were prepared to take riders down individually in the crane if the coaster couldn’t be restarted, however, a mechanic managed to get the ride going again and riders were lowered safely to the ground.

Craig Cannon / NBC Bay Area

A dozen riders were stuck on top of Six Flags Discovery Kingdom's Superman Ultimate Flight roller coaster this afternoon in Vallejo, Calif., for about two hours after it stalled near the top.

Vallejo fire crews said no one needed medical attention and all 12 passengers walked away safely.

It was unclear what caused the two-car train to stop, the Vallejo Times-Herald reported. Chan said the ride will be closed for a “thorough safety inspection.” She added that the ride will reopen when the inspection is completed at a time to be determined.

“If (a ride) stops, it usually detects something and it stops for safety reasons,” Chan said.

The ride, which opened at the park on June 30, holds two cars with six riders each and reaches a maximum speed of 62 miles per hour. According to the park's website, it features a launch coaster using electromagnetic propulsion, two upside-down twists and two vertical rolls. At 15 stories high, the coaster is ranked alongside rides with the tallest inversions in the world. 

The Associated Press contributed to this report. 

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