Millions of people in several states have been warned to take precautions, with some reports suggesting they should avoid windows for a period of time, possibly due to a heat wave or other emergency. The number of states and duration of the warning vary across reports, with some indicating 9 or 13 states are affected, and the time period ranging from 12 to 60 hours. The nature and scope of the threat are not entirely clear, with different outlets reporting different details.