Chilly weather brought five trains on the Confederation Line to a halt Saturday morning after cold temperatures created local power grid issues.
Repairs are underway and the trains will remain stopped until they can be safely removed from the light rail line, according to an afternoon update from the City of Ottawa.
Riders were able to get off the trains at stations on the line, the city said.
Rideau Transit Maintenance (RTM) sent technicians to investigate, with their initial inspections finding the frigid temperatures affected the overhead wires, according to the update.
Replacement R1 buses are running between Hurdman and Blair stations every five minutes. Three trains are also running between Tunney's Pasture and Hurdman stations every 15 minutes, the city said.
Somerset Coun. Catherine McKenney, who sits on the city's transit commission and is a candidate in this year's mayoral election, called the latest breakdown "disappointing."
"It has to work. It's not OK when it doesn't. And I would say it's even more important when it's bitterly cold," McKenney told Radio-Canada.
"To have that train break down, to have to walk anywhere or wait out in the cold, really discourages people from taking transit."
Service on the Confederation Line is expected to be impacted all day. The city said it was working with RTM to have normal service resume Sunday.
Ottawa had been under an extreme cold warning Thursday and Friday, but it has since lifted.