Blue Alerts are issued to help catch people who are believed to have wounded or killed local, state or federal law enforcement officers. Here are the criteria for a Blue Alert: A law enforcement officer must have been killed or seriously injured by an offender.

Phones buzzed across Texas just before 8 p.m. Wednesday with a high-priority emergency alert. But it wasn't about flooding, a storm, or a missing child. It was about a five-day-old shooting at an ICE detention center hundreds of miles away.

Texas is one of several states that use Blue Alerts, but what is it, and how does it differ from AMBER Alerts?