OAKVILLE, Ont. - A school bus ended up perched on a retaining wall next to an Oakville harbour after a morning crash that seriously injured the driver but left his two young passengers unhurt.

Police say the bus mounted the curb, struck a tree and smashed through an iron fence near Bronte Harbour at about 8 a.m. Thursday, before coming to a "precarious perch" atop the wall.

Emergency crews removed the unresponsive driver -- a 62-year-old Burlington man -- and the two uninjured children from the bus.

The children -- brothers aged 11 and seven -- were turned over to their mother.

The driver was taken to Oakville Trafalgar Memorial Hospital and then transferred to Trillium Health Centre in Mississauga where he was listed in serious condition.

Police are not releasing the names of the driver, the students or the school they were heading to.

The bus will undergo a mechanical inspection and investigators will also be looking at the possibility of a medical issue on the part of the driver.

A section of Bronte Road (between Lakeshore Road and Marine Drive) was closed for 3 1/2 hours while police investigated the incident.