TOKYO (AP) — A smartphone app developed by Japanese police is being widely downloaded by women trying to protect themselves from gropers on packed rush-hour trains.

The “Digi Police” app was originally issued by Tokyo police three years ago, but a function to scare off molesters was only added a few months ago. Since then, the app has reportedly been downloaded hundreds of thousands of times — unusual for a government-developed mobile application.

Women in crowded trains and other public places in Japan often face sexual harassment, but are typically too afraid to call out for help due to a sense of embarrassment.

With the app, victims can press a “repel groper” icon to produce a written message saying “There is a groper here. Please help.” With another press, the message turns red and a voice repeatedly says, “Please stop!”

The app includes an alarm and can notify a designated email address when used — a feature that can also be used by children and their parents.