The incident happened at the sheriff's firing rang on Leesburg Road around 8:20 a.m., a spokesperson for the county sheriff's office said.
"While we cannot provide more specific details at this time, we can confirm that the incident involved another deputy and occurred during a routine training exercise," the spokesman said.
One deputy was taken to a local hospital and is stable and out of surgery, the spokesman said.
Click here to follow Daily Voice Oakton and receive free news updates.