This is not an actual shooting.
"It's really challenging," said Officer Dave Gibson with the Nevada Department of Public Safety. "It's as close the real thing as you can get."
"Gunshot wounds, broken legs, I saw a role player with glass sticking out of their arms," said Trooper Jason Buratczuk, with Nevada Highway Patrol. "It gets intense. It's hot, they're wearing all that gear, carrying heavy guns, they're moving fast."
A siege can be terrifying.
“These officers have to make entry and see that carnage in that front lobby," Gibson said.
Officers never know what to expect.
“We think to ourselves. If there's one shooter -- there's two -- so we're always looking for two," Gibson said.
It's especially challenging in a building lot of floors and places to hide.
"We actually have to watch out for ourselves because if there are two that could be an ambush on us," Gibson said.
No matter the risk, officers have to remain sharp to look out for us when we need them the most.
“Every officer would be scared in that situation, but we have a job to do and that's to save lives," Buratczuk said