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.

Oklahoma Highway Patrol issues Blue Alert in connection with July 4 ambush in Texas. Benjamin Hanil Song, considered armed and dangerous, on Texas' 10 Most Wanted.

Benjamin Hanil Song, a former Marine reservist, is wanted in connection with the coordinated July 4 attack, according to authorities.

"During this attack, an Alvarado Police Officer was shot and wounded," according to the FBI notice. "On July 9, a federal arrest warrant was issued for Song in the United States District Court, Northern District of Texas,

A Blue Alert has been activated in Oklahoma for a man wanted in connection to an attack on an Immigration and Customs Enforcement (ICE) facility.According to th

The FBI said Song allegedly was involved at an attack on an officer on July 4 at Prairieland Detention Center in Alvarado, Texas.

Benjamin Hanil Song is accused of shooting an Alvarado police officer during an attack on the Prairieland Detention Center.

The suspect, a former U.S. Marine Corps reservist, is accused of joining 11 others in an organized attack against officers at the Prairieland Detention Center.

A Blue Alert was issued on Wednesday for a man accused of shooting an Alvarado police officer during an attack at a U.S. Immigration and Customs Enforcement detention facility on July 4, according to the Texas Department of Public Safety and the FBI.

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