Awakened by NWS (National Weather Service) alert
After suffering from insomnia for days, I was enjoying an easy sleep when I was awakened at 2 AM by a siren like sound issuing from my iPhone. It turned out it was a flash flood warning from the NWS! I got a similar sound a minute later from an android phone also in the bedroom. Apparently, the local authorities thought it was necessary to wake people up at 2 AM to tell them watch out for flooding on the roads. The android phone is being decommissioned and doesn't even have a carrier anymore, so the alert must've come through Wi-Fi or other means. On the iPhone, underneath the alert on the Notifications screen was a Settings button, but tapping this just brought me to general notifications--I do not see anything about local alerts there. A silent alert would be all right but a loud siren is ridiculous. I thought I had "do not disturb" turned on. I have the phone in my bedroom for emergency purposes.
iPhone 6 Plus, iOS 10