My house has a fire sprinkler system. Each nozzle is heat activated, in that the heat from a fire melts a plug allowing the water to flow. Only the hot valves activate, not everything.
The contractor told me which would I prefer, a sprinkler spraying some water around, or a firehose through the window?
That's why i specifically mentioned double-interlock preaction systems, where if someone hits the sprinkler and causes it to open, the only thing that comes out is compressed air (and a trouble/supervisory alarm sounds).
Anyhow, at the time I did some research and found that nobody had died in a fire in the US in a room that had working sprinklers. It's pretty darn compelling.