Toronto police have closed off a number of streets in downtown - near RBC offices - after several explosions and thick dark smoke was seen...

As DurhamRadioNews reports, Toronto Fire and Police on the scene in downtown Toronto after sparks, sounds of an explosion, and thick billowing smoke came from underground in the Yonge and King area.

Officials believe it’s hydro related and although some of the surrounding streets are closed, subway service isn’t affected. There is no indication it’s criminal in nature.

First Explosion...

Second Explosion...

.@CBCNews I swear in this one.

This was 20 seconds after first explosion. I had just walked across those grates. pic.twitter.com/MoJj4Aa10w — mike amsterdam (@plutoisnumber9) May 1, 2017

Toronto Fire is advising people to avoid the area of Yonge and King streets as they work to investigate multiple reported explosions. — TorontoNews (@torontonews3) May 1, 2017

Police are reportedly saying this is a 'hydro vault' explosion...

Toronto Fire advising people to avoid area of Yonge and King streets as they work to contain what appears to be hydro vault explosions — TorontoNews (@torontonews3) May 1, 2017

The smoke is significant...