A rapidly spreading overnight fire in Oshawa sent three adults to hospital with minor injuries and has left one resident missing as crews continue to search the severely damaged home.

Firefighters were called to a house near Bloor Street East and Simcoe Street South shortly before 4 a.m. Tuesday. On arrival, crews encountered intense smoke and flames that had originated in the basement and quickly advanced through the upper floors before breaking through the roof.

Police said three residents were taken to hospital with minor injuries, while three others had already made it out safely. One adult man who lives in the home has not been located, and firefighters are working to determine whether he escaped or is still inside. Search efforts have been slowed by extensive structural damage and cluttered conditions within the house.

No firefighters were hurt. Investigators have not yet identified the cause of the fire or confirmed whether smoke alarms were functioning, and police say it is too soon to determine if the incident is suspicious.

Bloor Street East remains closed between Albert Street and the Highway 401 ramp, and motorists are being advised to avoid the area.

Update – The missing person has be found.