Memories of the Aurora theater shooting can seem inescapable. Those moments can be even harder to shake for people directly involved like the police officers who responded to the tragedy.

"I don't think you can ever not think about it on a daily basis," Officer Jon Marek said as he remembered vivid details about what happened on July 20, 2012. "I parked exactly at this spot. I went this exact route."

Memories of what happened on that day five years ago are often more vivid when similar tragedies happen around the world like the one that happened Sunday night in Las Vegas.

"You hear the same sounds that we heard," Marek said.

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Lieutenant Stephen Redfearn first learned of what happened in Las Vegas from a friend who called him Monday morning.

"She said, 'Hey, are you OK? Have you seen what happened,'" Redfearn said. He told 9NEWS it's pretty common for friends, family and colleagues to check in on him when mass shootings occur because they "tend to bring back some of the things we experienced here in 2012."

Just as his friend did for him, Redfearn reached out to the other officers he worked with during the theater shooting to make sure they, too, were OK, including Marek.

Marek said he first heard what happened in Las Vegas while watching the morning news. Even though he was not yet on the clock, he said he viewed the images as if he was one of the responding officers to that specific tragedy.

"You just wonder -- in the nature of our job -- what could I have done to help," he said. "Is there anything I could have done?"

Meanwhile, Redfearn said he had a hard time even looking at a TV.

"I won't watch the actual coverage of the cell phone footage of the scene or anything like that," Redfearn said. "I think I probably share the sentiment of a lot of the first responders that there's nothing necessarily beneficial that's going to come from watching some of the footage."

While he can't bring himself to watch what actually happened in Las Vegas, Redfearn told 9NEWS there is something police officers across the country can learn from mass shootings.

"We have to continue to train, we have to continue to analyze what occurred here, what occurred in Orlando," Redfearn said. "We have to constantly be reevaluating the way we respond, our tactics, our training. Because as we saw last night, clearly the bad guys evolve. They change their tactics as well, so we're very remiss if we don't learn something from each of these then kind of fix our response if there are things we can do better."

Redfearn said he and the Aurora Police Department will be reaching out to first responders in Las Vegas just as they did after the shooting at Pulse Nightclub in Orlando, last year.