• This article is part of a larger story on how the Palo Alto school district reviewing its response to threats at its campuses.

After two students shot and killed 13 people and then themselves at Columbine High School in 1999, law enforcement's approach to responding to campus shooters shifted dramatically.

Instead of calling a SWAT team to enter a school, police officers started to receive training on how to enter the fray themselves, said Palo Alto Police Department spokesman Capt. Zach Perron.

"After Columbine, response procedures for law enforcement everywhere changed, and the Palo Alto Police Department was no different," he said in an interview with the Weekly. "There was a recognition and a desire to change to save lives."

Officers' training completely changed, he said, to focus on "preserving as much life as we can, which means in most circumstances that your patrol officers, as soon as they get on scene, are going to make entry to that school to try to save lives."

Two school resource officers from the police department who work with the schools are the only armed personnel affiliated with the district.

In the Parkland, Florida, mass shooting, an armed resource officer who arrived at Marjory Stoneman Douglas High School was widely criticized for not entering the building or trying to engage the shooter.

In 2016, the Palo Alto Police Department became the first police agency in Santa Clara County to train all of its officers on the county's new active-shooter protocol, Perron said. The protocol aimed to improve coordination between police and fire department personnel to get medical help to the wounded more quickly. In November 2016, Palo Alto police officers, fire personnel and others gathered at a Veteran Affairs training facility in Mountain View to practice their response to simulated shootings, with a focus on how to "safely escort emergency medical personnel to any victims that may need aid," Perron said.

As of last fall, the Palo Alto Fire Department was the first county fire agency to train all of its employees in the new protocol, Perron said.

All Palo Alto police officers receive the same active-shooter training, Perron said, whether or not the individual is a school resource officer. One of the two school resource officers may be on a campus when a shooting happens, but any officer is expected to respond immediately to an incident. All officers keep maps of the schools in their patrol cars, Perron said.

As of three years ago, all Palo Alto police are equipped with a semi-automatic AR-15 rifle in their patrol cars so that they can immediately respond to shootings and any other tactical situation that would require engaging a suspect from farther away, Perron said. Previously, officers went through a special training to carry the rifles.

Perron said that every shooting, on schools and elsewhere, provides the police department an opportunity to reflect on its procedures while avoiding any "knee-jerk reaction."

"We're acutely aware that every potential incident that happens like this gives us a chance to review our procedures and say, 'Is there anything that we need to be tweaking? Are the tactics of the suspects changing? Were this one to happen in our district, are there any changes that we would need to make to our operational procedures to ensure we can meet our goal, which is saving as many lives as we can?'

"That's a constant examination that occurs after any of these major incidents," he said.