When it comes to how police respond to mass shootings, there's a big difference between present day versus decades ago.
Twenty years ago, on the day two gunman executed a massacre at Columbine High School, the SWAT team waited to gather its whole team before going in.
The result: it took two hours to get to the library, where many students died.
Today, police across the country don't wait. They make entry with small groups, with the goal of stopping the killer immediately.
Police say that simple change has saved lives.
Since the tragedy at Columbine High School, the school safety and security market has exploded. People and companies are peddling all kinds of devices, from smoke cannons that fill a hallway with smoke to rocks or hockey pucks to throw at an attacker and even bullet-proof backpacks.
Bill Woodward, a school violence expert, says when you have to use those, it's too late.
Woodward says schools should create a climate where everyone feels comfortable sharing concerns. That goes for administrators and students. Schools should adopt bullying programs proven to work, not ones that just sound good, Woodward says.
“They have a curriculum that you have to follow to put that program in place in the school,” he says of the anti-bullying programs. “They are not somebody who comes into an assembly and just gets everybody excited about stopping solving bullying. If you don't have a curriculum, then I’ll tell you that program is probably not evidence based.”
Schools must also make sure students know how to report concerns.
In 80 percent of school shootings, the shooter talked to someone or somehow leaked their plans ahead of time, according to the Center for the Study of Prevention and Violence. However, the shootings still happened.
Ninety-three percent of the time, there were warning signs that someone saw, but often times, that information didn't make it to the school safety team either because students didn't know how to come forward or bits of information wasn't shared collectively. Bottomline, authorities don't have the big picture.
"It's the kids that know something that kids may see it on social media. But if you're not trained as a kid of what to do with that information, I know for myself, I wouldn't know what to do and I probably would do nothing,” says Beverly Kingston, violence director with the Center for the Study and Prevention.
Both experts say to parents: get a written copy of your kids' school safety plan. Read it and see if it involves each of the following: police, teachers, students and mental health professionals.
If you have questions, ask the principal. Additionally, talk to your children about how to report something to someone for help.