The Daily News reports that around 8 p.m. on Wednesday the woman was at Lake Sacajawea when a man approached her aggressively while masturbating and suggested she should watch him.
Instead the woman furnished her gun.
Longview police detective Kyle Sahim says officers haven't found the man Thursday evening but are investigating several suspects.
The man involved in the Lake Sacajawea incident was described as a white male in his early 20s with short dark-blond hair. The victim called police later in the evening, saying she was looking at an online database of local sex offenders and believed she recognized the man she saw at the lake.