There was a large explosion a few streets down from where I live. I think I might have heard (or felt it), but I can’t remember for sure. I know that later, when I learned of the blast, there was a really strong lightning display to the south of us. At first, it didn’t look like lightning — I thought maybe the light show was the refinery burning — but a couple of spectacular bolt strikes settled that.
I think I might have shrugged the blast off as thunder, which would have sucked has there been any actual toxic fumes (not a far fetched idea, as Mississauga is no stranger to toxic explosions).