A Hydro Ottawa vehicle is seen in this undated photo. (CTV Ottawa)

Hydro Ottawa says a loss of power supply from the provincial grid is responsible for a massive power outage in Ottawa's west-end.

Power was restored to the areas of Westboro, Lincoln Fields, Britannia Heights, Woodroffe and Baseline areas at approximately 4:30 p.m.

At one point, more than 21,000 customers were without power when the power went out just after 3 p.m.