https://apnews.com/477b5b53f6a3423885b521b648c3e560

SALEM, Ore. (AP) — The words blasted to cellphones around Salem, Oregon were ominous: "Civil emergency. prepare for action."

Within half an hour, a second official alert clarified the subject wasn't impending violence, but toxins from an algae bloom, detected in the city's water supply.