The siren was a tsunami warning system. The natural reaction would be to head for the hills. https://www.theguardian.com/us-news/2023/aug/17/hawaii-fires-maui-schools-search-death-toll
@Gaythia my understanding is that's not quite accurate even though the thought process was as you say. The siren definitely was intended to be an "all hazard" warning and not just a tsunami siren; it's described that way on official state emergency response pages and in discussion of the system from before the fire. But I think the idea that in the moment many people wouldn't realize that distinction and would react *as if it was* a tsunami warning is at least plausible. So a minor point here.
@mrcompletely I agree. I think that is the problem with sirens, insufficient information. The issue with cell phone alerts is not knowing how many people have them or have them handy. And in cases like this one, having an escape route is crucial. And, if everyone who had a car had tried to exit all at ones, gridlock would have been even worse than it was.
@mrcompletely the evacuation going on in Yellowknife, NWT Canada is an interesting case in point. The mayor was telling people it was not time to evacuate all the way up to when it was. To do that, they had to protect the long exit route, with pilot cars, tow trucks and fueling stations en-route, and to come up with air evacuation for those who could not make the drive. I think that they were trying to avoid a panicked exodus jam up.
@Gaythia I read about that - it does seem from the outside like they're putting a lot of thought and effort into those logistics. Hopefully they are managing it as well as possible. The Maui situation is utterly tragic and hopefully learn well from it. The narrow, bottlenecked evacuation route there has long concerned me. There are simply no alternate land routes at all.