What are Blue Alerts on my iPhone?

What are Blue Alerts and why they are sent:

1. A law enforcement officer must have been killed or seriously injured by an offender.
2. The investigating law enforcement agency must determine that the offender poses a serious risk or threat to the public and other law enforcement personnel.
3. A detailed description of the offender's vehicle, vehicle tag, or partial tag must be available for broadcast to the public.
4. The investigating law enforcement agency of jurisdiction must recommend activation of the Blue Alert to the Texas Department of Public Safety (DPS).