As the Guadalupe River swelled from a wall of water heading downstream, sirens blared over the tiny river community of Comfort — a last-ditch warning to get out for those who had missed cellphone alerts and firefighters going street-to-street telling people to get out.

It’s just before noon and several news crews are gathered outside the fire hall in Comfort, Texas, their cameras pointed at a yellow siren high on a pole and set to go off every day at midday.