Toronto Hydro says power has been restored to approximately 2,400 customers who were affected by a widespread outage this morning.

The utility says the outage, which impacted residents in the area bounded by Dufferin Street, Avenue Road, St. Clair Avenue and College Street, was caused by a supply issue with Hydro One.

Hydro One spokesperson Ani Bekmezian said the exact cause of the outage, which began at 4:15 a.m., has not yet been determined.

She said maintenance crews are scene investigating.

The outage also affected subway service on Line 1.

Subway service was suspended between St. George and Lawrence West stations but regular service resumed at around 6:15 a.m.