Blue Alert issued in Phoenix: What does it mean?

PHOENIX (3TV/CBS 5) -- Did you get a "Blue Alert" on your phone this afternoon and evening? The alerts were issued after two DPS troopers were shot at. One 17-year-old suspect was captured, but a second suspect remained at large.

However, many people in the Valley were puzzled by the alert. The message goes out over television and via Wireless Emergency Alert System (WEA) which sends out a tone and message to your cell phone.

"The purpose of these emergency alerts in general is to do 2 things; to protect the public and to protect the public servants," said Chris Kline, the president of Arizona Broadcasters Association.

The Arizona Broadcasters Association partners with state agencies to make sure emergency messages get out to the public correctly. "In the case of Blue Alerts, really, this comes down to using the public at large to help take care of a public servant that's in trouble and to use their eyes and ears to track down someone who may have done something pretty bad to someone that we all trust on a daily basis," Kline explained.

The Arizona Department of Public Safety (DPS) oversees the system. The other alerts are AMBER, for abducted children who might be in imminent danger, and Silver, for "when a person with specific cognitive or developmental disabilities, as defined by statute, or a person the age of 65 or older goes missing."

With a Blue Alert, all conditions must be met in order for it to be issued. The criteria include: a law enforcement officer was seriously hurt, killed or assaulted with a deadly weapon and the suspect is at large, there is a suspect vehicle description or license plate, and the suspect poses an imminent threat to the public or other law enforcement officers.

"It works fine if everybody does what they're supposed to do and the public notifies and says, 'Hey we see him.' We don't tell the public to go and chase the criminals," said Tom Berry, the founder of the Blue Alert System.

Berry, a former military officer, came up with the Blue Alert System in 2008. By 2015, it became federally recognized. Berry says the Blue Alerts are issued so rarely that he becomes inundated with inquiries about the system each time it's sent out.

"We only have it every so often, which is a good thing, don't get me wrong. I'd hate to have Blue Alerts every other day where people are saying, 'Oh there's another Blue Alert, there's another Blue Alert.' That means another officer was seriously injured or was killed," Berry said.

Berry says that the alerts can be targeted to a specific area, like Amber Alerts. "If they think the person really is still in Phoenix, why bother the people in Tucson?"

If someone wants to opt out of the Blue Alerts, they can turn off the emergency alert system by going into their system preferences on their phone.

The Blue Alert System foundation also takes care of families of fallen officers killed in the line of duty, and donates bulletproof vests to police K9s.