CENTENNIAL, Colo. -- An Arapahoe County Courthouse security officer accidentally fired his handgun, injuring a colleague Wednesday morning after he ran the weapon through an X-ray machine, authorities said.

The security officer, Christopher Reed, 26, was charged with misdemeanor reckless endangerment, Arapahoe County Sheriff Grayson Robinson said in a news release.

Reed worked for Olympic Security, a contractor that provides security for the District Courthouse at 7305 South Potomac St, in Centennial, Robinson said.

The shooting occurred at 7:28 a.m., before the courthouse opened to the public, he said.

Reed told deputies responding to the report of an accidental shooting that he placed his service weapon, a 9 mm semi-automatic handgun, through the X-ray machine in the lobby in an attempt to calibrate the machine, Robinson said.

"Olympic Security has verified that this is not an approved machine calibration technique," Robinson said.

As the handgun exited the X-ray machine, Reed was re-loading the bullet magazine into his handgun when it accidentally fired a bullet into the courthouse floor, the sheriff said.

Another Olympic security officer standing near Reed was struck by a small piece of shrapnel. That security officer was treated for a minor injury and released, Robinson said.