Fairfax County police on Sunday arrested an off-duty U.S. Park Police officer who authorities said unintentionally shot and killed another off-duty Park Police officer while “dry firing” a gun in McLean.

Police said they charged Alexander Roy, 25, of McLean, with involuntary manslaughter in connection to the fatal shooting of 22-year-old Jesse Brown Hernandez, of McLean, early Sunday morning.

Around 12:20 a.m., police said they responded to an apartment on the 1700 block of Old Meadow Road where they found the victim suffering from a gunshot wound.      

Investigators said that Mr. Roy was trying to dry fire a gun — where someone pulls the trigger on an unloaded firearm — but it turned out the weapon was loaded.

Police said the bullet struck Mr. Hernandez in the upper body. He was pronounced dead at the scene.

Four people were inside the apartment at the time, with three of the people being off-duty Park Police officers. Police said that alcohol is thought to be a factor in the incident.  

Mr. Roy is being held without bond at the Fairfax County Adult Detention Center.

• Matt Delaney can be reached at mdelaney@washingtontimes.com.