Vancouver's light-rail system the SkyTrain was out of operation for five hours on Monday noon, leaving thousands of passengers stranded in the train cars.
The spokesperson for the region's transport authority, Translink, said the five-hour shutdown was due to a "technology issue," without giving further details.
Jiana Ling described the incident as "unfortunate" in a statement, but added: "We're still at 95 percent reliability on the system, which is quite high."
There was no immediate official estimate of the number of passengers affected Monday, but it is thought to have been in the thousands as commuters were escorted off trains and out of stations.
Just four days prior to the incident, SkyTrain lines ground to a halt at the height of rush hour, stranding passengers for three hours. SkyTrain President Fred Cummings said the accident was the result of a "computer problem."
SkyTrain was built in 1985 and is the main public transportation in Vancouver, carrying passengers across the city and to nearby towns.