Three flashing incidents have been reported aboard Metro trains during the past two weeks, say Metro Transit Police.
One victim snapped a photo of the man who exposed himself to her, she said. Police have shared the image with the public.
The incidents have occurred twice on the Red Line near the Dupont Circle and Brookland stations, and once on the Orange Line in Virginia.
The victims told police the man carried a blue duffel bag and may have held it over his lap before exposing himself.
Some riders said they were not surprised by what was happening, but rather the timing -- each of the incidents happened during the day, between 9 a.m. and 3 p.m.
"I don't worry during the day," one rider said. "At night, I'm usually more cautious."
So far this year, Metro police have received 57 reports of indecent exposure on board.
"The difficulty with these kinds of incidents is that they're chronically unreported," Caroline Laurin with Metro said.
One victim spoke with News4 about her experience. She's not believed to have fallen victim to the man whose photo police released this week.
"I looked up to check what station I was on and when I looked back down to what I was watching and then I looked over to his side, I saw you know his genitals were out," she said.