Barrie Firefighters were called to the Marina Bay Condominiums on Ellen Street to investigate reports of smoke in the high rise.
The call came in around 2:30 p.m. Thursday.
"There is smoke throughout numerous floors in the building. Crews are still trying to determine the source," said Barrie Fire Public Information Officer Samantha Hoffmann.
County of Simcoe Paramedics were standing by on scene but there were no reports of injuries.
Hoffmann later reported the smoke was caused by an overheated elevator which is now out of service.