The first responders witnessed a fire in a house on Avenue Road, near Kilbury Street, shortly after 8:30 p.m.
Firefighters had to enter the house and encountered intense flames and smoke inside.
Three occupants tried to escape by going to the roof and were rescued there, the Toronto fire said.
No injuries were reported.
Most of the fire has been extinguished and crews have completed primary and secondary investigations.
The cause of the fire is unknown.
