Subway service has resumed at Union Station after heavy rains flooded the transit hub, forcing thousands of commuters to make alternate arrangements.

Two streetcar routes -- the 510 Spadina and the 509 Harbourfront – are also back on track after Friday's flooding brought service at the station to a halt.

Emergency crews were called to the station shortly before 1 p.m. after a mixture of rain and sewage water cascaded over subway tracks, carrying a foul stench with it.

Water had reportedly reached heights of 30 centimetres in some parts of the station.

As a result, transit service from Osgoode to Bloor Station was turned back. Commuters formed long lines outside in the rain, waiting for shuttle buses to transport them to the next available station.

Officials have said the cause of the flood was a backed-up storm sewer.