Smoke drifted over the Toronto skyline yesterday afternoon as firefighters battled an electrical fire on the roof of the Air Canada Centre, home to the Maple Leafs and Raptors.

Toronto fire officials said the blaze was believed to have started in the lighting system for the arena's rooftop helicopter pad. About 50 firefighters responded at 3:30 p.m. and the fire was brought under control in about three hours.

Damage was estimated at about $50,000.

Downtown streets around the arena were blocked off by firefighters and police, causing traffic snarls until the fire was under control and emergency crews could leave.

Lake Shore Blvd. W., southbound Bay St. and York St. were blocked off until about 6:30 p.m. Northbound Bay St. opened at about 5:30 p.m.

There was some concern about whether the roof structure was weakened and about water damage to the building's interior.

However, Toronto fire department officials said the building seemed to be in good condition. Further investigation of the damage is expected.

There were no events under way at the sports and entertainment complex at the time of the fire and no one was hurt.

Air Canada Centre management could not be reached for comment yesterday on whether the facility would need to close temporarily for repairs. The next event scheduled for the centre is a performance by Asian entertainers Alan Tam and Hacken Lee on Aug. 21.

Some GO buses arriving and departing from the new Union Station bus terminal on Bay St. experienced minor delays shortly after 4 p.m. as emergency crews battled the fire. GO trains were not affected.

In July, 1988, firefighters battled a blaze at another landmark sporting venue. 

The SkyDome roof suffered about $350,000 worth of smoke damage during construction when a welder's torch set fire to plastic covering materials on the sixth level and immediately spread to the roof. No one was injured.