UPDATE (1:17): A clarification: There's no flooding on floor 6, and only about one-third of floor 5 is flooded.
UPDATE (1:03): A public safety officer tells Spec's Sarah Darville that a water line burst between the fifth and seventh floors. It seems that the broken water line—instead of or in addition to the sprinklers—has contributed to the flooding.
UPDATE (12:59): Here's what the fifth floor looks like:
