DENVER — Police response to school shootings has evolved since the shooting at Columbine High School in 1999.
"Training has significantly changed since Columbine," Douglas County Sheriff Tony Spurlock said.
In 1999, Spurlock was one of the deputies who responded to the school shooting. Back then, officers were trained to set up a perimeter and wait for SWAT. That's why it took more than 40 minutes for police to go inside during Columbine.
"If you can intervene and draw the attention off of the victims to you as an officer, the likelihood of reducing the number of victims that the person would be able to create is significant," he said.
Now, in Colorado, officers are trained to not wait for backup, but to go in as fast as possible after they arrive on the scene. That's what deputies in Douglas County did in 2019 when two teens went inside STEM School Highlands Ranch with guns.
"The first officer that arrived on the scene made an assessment of where the shooting took place, communicated that, and within -- literally inside within two minutes, we had a number of officers in the school addressing the target," Spurlock said.
Because of Columbine, entering the building right away is part of the training every officer in the state must go through to be certified. It's a tactic they felt was necessary to save more lives.
Spurlock said he couldn't speak on the shooting in Uvalde, Texas because investigators haven't released many details about the response.
There are questions about why it took so long for a tactical team to enter Robb Elementary School after a shooter walked inside.
The Texas Department of Public Safety said officers went inside minutes after the gunman but moved back after he fired at them.
According to investigators, a U.S. Border Patrol tactical team went inside the school an hour later and shot and killed the suspect.
SUGGESTED VIDEOS: Texas elementary school shooting