It's a dark day for the Los Vegas Police Department on CSI: Crime Scene Investigation.

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A lone teenage gunman is on the loose inside the LVPD's own office during "The Fallen," and it's up to D.B. Russell (Ted Danson) to try to get the young murderer under control. With 1 dead officer, 4 wounded, and another teen with a bullet in his stomach, Russell will have his work cut out for him.

"Not a good day in the police department!" director Louis Milito tweeted during filming, later adding that the "PD is supposed to be safe..."

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Behind-the-scenes photos show that the police department will be turning out in full riot gear to help take back their home (view photos here). As officers and detectives attempt to take down the shooter in a hail of bullets, Russell's only defense will be his words.

Unfortunately, the killer is prepared to die and he doesn't seem to care how many people he takes down in the process.

"You think I didn't know I was going to die today?" the teen asks Russell in a new sneak peek (see video below).

Find out if Russell makes it out of the LVPD unscathed when CSI airs Wednesday at 10 p.m. ET on CBS.

Tags: CSI: Crime Scene Investigation CBS television