An off-site power surge stalled the Dallas Zoo Monorail Safari on Wednesday afternoon, stranding dozens of passengers in mid-air for the third time in as many years.

The passengers were trapped about 12 feet off the ground in the open-air cars for about an hour while zoo officials tried to restart the train and await rescue help from Dallas Fire-Rescue.

[[270157691,C]]

Zoo officials handed up water and snacks to the stranded passengers. Once DFR arrived, the 48 passengers and the driver were escorted down the ladder to the ground below.

A power surge caused the slow-moving monorail to unexpectedly stop Wednesday afternoon, Zoo officials confirmed to NBC 5. The cause of the surge is unclear, but zoo officials told NBC 5 that several barns also lost power.

[[270040831,C]]

The monorail is expected to be closed through Friday while zoo officials examine the conditions of the track and trains.

The monorail is 24 years old and carries hundreds of thousands of riders each year, according to zoo officials. Long term, the zoo is looking to replace the monorail, but it will need to be privately funded.

This is the third such incident that has stranded passengers on the monorail in as many years.

On Feb. 13, 2013, 93 people were stranded due to a monorail malfunction at the Dallas Zoo.

And in September 2011, 30 people, babies among them, were rescued from a monorail that carries passengers through a 20-minute tour of the Wilds of Africa exhibit.

No injuries were reported.