'We were about four minutes into the ride, and it just stopped,' said Cristina Minter. 'Next thing you know, the fire department came and took my baby and we were on the ground.'
Oncor is looking into what's described as an external power surge at 11:37 a.m..
The Zoo said the monorail did exactly what it was designed to do on its leisurely journey around the Wilds of Africa exhibit slow down and stop.
Dallas Fire-Rescue personnel used ladders to lower the passengers 12 feet from the train.
Zoo officials said the monorail ride would remain closed until at least Friday while engineers inspect the 24-year-old attraction and make any necessary repairs.
The zoo said it is looking at long-term options for the Wilds of Africa exhibit which include replacing the monorail.