Two Loudoun County sheriff's deputies confronted Mhai Scott, 38, an employee at the Sterling Costco, after she began acting strangely near the end of her shift Wednesday afternoon.
Scott brandished a knife at the two officers, who police declined to identify, and when she ignored multiple commands to drop the weapon, the deputies attempted to subdue her using a taser.
When that failed to stop her, one of the deputies fired his gun several times, killing her.
The second deputy was injured in the leg by a gunshot, possibly a ricochet from the other deputy's weapon, Loudon County Sheriff Mike Chapman confirmed in a briefing to media.
"The second deputy received a leg injury and it appears as though he's going to be fine," Chapman said. "He's at the hospital right now.
"It's possible that the ricocheting bullet hit the second deputy."
Robert Krause, an optometrist who works in the building and witnessed the incident, told Leesberg Today he heard five gunshots and later saw the injured deputy taken from the store on a stretcher.
Krause said the injured man was on his cellphone.