Updated

About 100 people have been rescued without injury by firefighters after a monorail at the Dallas Zoo stopped operating.

Dallas Fire Rescue spokesman Jason Evans says as many as five extension ladders at a time were used to remove the passengers Saturday.

Evans says firefighters responded to a 911 call about 3:30 p.m. after an unspecified malfunction caused the train to stop moving.

He says the 30-minute rescue was made easier because the monorail stopped at a point that allowed for easy access to the passengers.

The zoo's website says the monorail is the only one in the U.S. that can "climb and turn, taking guests on a one-mile tour through bush, desert, forest, woodland, river and mountain environments."