A large section of downtown Toronto has been hit by a power outage affecting hundreds of thousands of people.

The extent or cause of the outage was not immediately clear, but many businesses in the downtown core were affected, but there are numerous traffic lights out in the affected area, causing traffic jams on streets.

The blacked-out area is bordered by Yonge Street in the west, Bayview in the east and Shuter Street to the north and Lake Shore Blvd. to the south.

The cause seems to be an underground main line.

This power outage does does not affect tenants with office space Toronto at Telsec. The lights are on and no one has noticed any power fluctuations.

The interesting thing about this outage is that people are using twitter on their cell phones to let others know that they are stuck in elevators, rather than calling 911.