A St. James Town highrise that is home to as many as 1,000 people could be without power until Thursday.
Officials think they will need at least that long to determine what went wrong inside 260 Wellesley St E Tuesday and how long it will take to fix.
The city says a burst pipe in the building's garbage disposal room caused water to leak into an electrical room. Toronto Hydro was ordered to cut he building's power to ensure that there wouldn't be a "catastrophic or prolonged" power outage.
Deputy Fire Chief Jim Jessop opted not to evacuate the 33 storey building, but allowed people who wanted to stay put in the apartments the option to do so.
"Given the time of day, given the number of occupants of the building, we believe that for a short term, we can make the building safe," Jessop told reporters Tuesday night. "To tell everyone to start walking down in the dark right now, is going to put more people in danger than implementing these short term measures."
Officials are scheduled to meet no later than 8.a.m. Wednesday for an update and to re-evaluate the decision not to evacuate the building.
It's unclear how many residents of 260 Wellesley slept in their dark, heatless apartments Tuesday night.
Dozens of employees of the Red Cross, Toronto Fire, and a security firm hired by the building's management company were tasked with checking up on residents and making sure there was no fire risk. They were expected to deliver extra blankets, food and water to drink and to flush toilets.
Mayor John Tory said the city would be monitoring the temperature inside the building. He discouraged residents from using candles or stoves to keep their apartments toasty.
The Wellesley Community Centre at 495 Sherbourne St has been opened so people can warm up, get something to eat or drink, charge their phones and stay the night if they need to.
The sudden loss of the comforts of home is familiar to some residents of 260 Wellesley.
Local councillor Kristyn Wong-Tam says 26 of them had found new homes in the highrise after being forced from their units at 650 Parliament St following a damaging fire last August. The management company which runs both apartment towers doesn't expect anyone will be able to move back into 650 Parliament until spring.