Officers are usually the first to arrive at a shooting and many say so much has changed in the way they respond since the massive school shooting at Columbine.
Many police departments and school districts train for these situations and many say they think about ways to improve safety daily.
All officers say they rely on training, training that includes disregarding their own safety at times in order to make sure the shooter is stopped.
In Connecticut, a massive number of police officers responded to the scene of a school shooting.
In past the four months our area has seen active shooter drills at Parkland High school and DeSales University.
There was also the threat of an actual shooter called in to Parkland in September that later turned out to be untrue.
"Law enforcement across the country has changed their tactics on how we deal with active shooters," said Bethlehem Police Chief, Jason Schiffer. "We're trained now to quickly arrive and assemble a team, go in and remove the threat, take the shooter out."
The Bethlehem Police Department just finished active shooter training a few weeks ago.
Seeing the horrific scene in Connecticut not only makes Schiffer think about his own children but those in the 22 schools his force watches over.
"We have our school resource officer and he's been taking a lot of our street supervisors and patrol officers through schools to get familiar with all the layouts of the schools," said Schiffer. "We have books on every single school with photographs."
"As an educator and as a high school principal, I unfortunately experienced a shooting in our school where a student came in and took his own life," said Joseph Roy, Superintendent of the Bethlehem Area School District.
That shooting took place at Springfield Township high school in Montgomery County in 2006.
Since Roy says he's works with the police to help first responders as well.
Each school has secure doors, and practices lock down drills.
"Security has to be a daily habit," added Roy. "It's what you do every day."
Police tells us one part they can't train for is the emotional impact that a school shooting scene will have on them while they are doing their job.