Law enforcement officers surrounded the Parkland, Florida, high school to keep the students safe after a shooter broke into the school Wednesday afternoon.
The way they respond is much different from one of the first school shootings in Columbine, Colorado.
"Identifying where that threat is ... and eliminating that threat," former FBI agent Ricky Hill said.
Law enforcement immediately jumped in to help in Parkland, but that wasn't always the case.
"As a law enforcement official, a retired law enforcement official, that's my first thought: What training have they gone through so they can ensure the safety of as many individuals as they can?" Hill said. "Law enforcement, starting with Columbine and ending with today, have changed the way they approach these types of events."
Hill said from a law enforcement perspective, the 1999 shooting at Columbine High School was much different than Wednesday at Parkland.
"In Columbine, when the tactical team, the SWAT team arrived there, they were going to stand down, if you will, and prepare themselves to understand the situation before they enter," Hill said.
Now, they're going in immediately.
"In today's environment, law enforcement are being trained not to wait," Hill said.
Then the threat is immediate, they respond with the same speed, and ideally, with four officers, he said.
"From a tactical standpoint, using that number four, it gives them that ability to cover all four corners of an entry point, so if you enter in, you've got your north, east, west and south," Hill said.
Another big change from Columbine: The training is now consistent for different law enforcement departments. Before, it wasn't coordinated, and Hill said that caused a problem.
"Police departments, law enforcement agencies, federal, state or local, they may have trained for a mass shooting type of event, but they trained individually to their department, it wasn't coordinated or consistent across the training platforms," Hill said.
Now, that training is consistent.
"If Knoxville Police Department trained, they are going to train the same way the TBI, or the state police, or the FBI would train in their tactical procedures," he said. "So if one individual law enforcement personnel should arrive to the scene first, they know exactly what the other person is going to do because they've had the same type of training."
Hill said everyone can help prevent these types of situations by reporting issues like bullying or threatening behavior.