All lanes of the Don Valley Parkway reopened around 7 p.m. Friday evening, following a "police investigation".
Police are releasing few details, but witnesses reported seeing someone standing on a platform underneath the Bloor Viaduct around 4 o'clock this afternoon.
The investigation also affected subway service on Line 2 between St George and Broadview stations.
In a tweet posted shortly after 7 p.m., Toronto Police noted that things were resolved safely: "We are very pleased to say the medical situation on the Prince Edward Viaduct has been successfully resolved with no injuries to anyone involved, including First Responders."