I think it was more like a hour. The crowds supposedly got in the way, which sounds like BS to me. Now the fire fighters are saying they were there at the start, helping the people in the building get out of it. Apparently a river runs right through the complex, ironically.
Notre Dame is on an island in the Seine. It's the oldest part of Paris; the city there dates back to Roman times.
it’s been said they were evacuating but also scrambling to remove what artwork and such that they could from the building before they poured the water on.