This just happened about an hour ago! They are saying it's hydro vaults but in the news it's being described as several loud explosions coming from grates and the power is out in a few of the buildings. :O
_http://www.cp24.com/news/heavy-smoke-pouring-from-grate-closing-king-street-in-financial-district-1.3393252
ADDED: This article has more detail.
_http://www.cbc.ca/news/canada/toronto/black-smoke-pouring-from-beneath-scotia-plaza-in-heart-of-toronto-s-business-district-1.4094416
_http://www.cp24.com/news/heavy-smoke-pouring-from-grate-closing-king-street-in-financial-district-1.3393252
Heavy smoke and the sound of a possible explosions near the Scotiabank plaza building in the Financial District on Monday afternoon have closed off King Street West.
Plumes of brown smoke were seen rising from a sewer grate along King Street between Bay and Yonge streets shortly after 5 p.m., Toronto police said.
"What it appears to be at this point is likely a hydro vault," Capt. Adrian Ratushniak, a spokesperson for Toronto fire told CP24. "Explosions are continuing at this time."
He added that it's likely a contained hydro vault and isn't a risk to public safety.
Witnesses said they heard several loud bangs which sounded like explosions.
King Street is closed between Yonge and Bay streets.
Toronto Transit Commission spokesperson Brad Ross told CP24 that Line 1 subway service isn't affected by the incident. Streetcar routes however are being diverted.
More to come...
ADDED: This article has more detail.
_http://www.cbc.ca/news/canada/toronto/black-smoke-pouring-from-beneath-scotia-plaza-in-heart-of-toronto-s-business-district-1.4094416
An explosion that echoed from beneath the heart of Toronto's business district at King Street West and Bay Street was caused by a blown hydro vault, a senior fire official told CBC News.
Plumes of black smoke poured underneath Scotia Plaza around 5:15 p.m. as commuters leaving work for the day began screaming in the confusion.
Witnesses at the scene reported screaming as the noise continued for several moments. Toronto police have not yet said what caused the sound of the blast, but a fire official on the scene told CBC News that the hydro vault — which contains high-voltage transformers — blew.
Officers descended on the area Monday afternoon and blocked off King and Bay. Despite those efforts, many people stayed close enough to document the chaos.
No one has been reported as being injured, Const. Allyson Douglas-Cook said.
Police have since closed off Front Street West and Adelaide Street at King, which itself is closed between Yonge and Bay streets.
The King subway station is close to where the smoke can be seen, but TTC spokesperson Brad Ross said the subway there is not affected.
The 504 and 514 streetcars — which travel along King — are diverting along Queen Street West between Spadina Avenue and Church Street.