A flasher took off running when a woman pulled out a gun and pointed it at him.
The woman was at Lake Sacajawea, in Longview, Washington state in the US, when a man approached her aggressively while masturbating and suggested she should watch him.
Instead the woman produced her gun.
Detective Kyle Sahim said officers have not found the man but are investigating several suspects.
The man was described as white, in his early 20s, with short dark-blond hair.