The Mexican city of Juarez has been dubbed "the capital of murdered women": since the 1990s, hundreds of women have been raped, killed and dumped in the desert, or simply disappeared without a trace.
Now the border city, which sits across from El Paso, Texas, is fighting back by launching an application that turns women's cell phones into panic buttons.
The app, called "I Am Not Alone" ("No estoy sola," in Spanish), lets users send an alert to their emergency contacts by shaking their phones or clicking a button.
It does not require a data plan, instead sending text messages with a link that enables the recipient to see the user's location on Google Maps.
"Wherever you have cell phone coverage, you can use the app," said Miguel David Diaz de Leon, technology and communications director at Juarez City Hall.
"Help, I have an emergency. This is my location," say the messages.
The app continues sending them every five to 10 minutes, or until the user deactivates them.
The app is currently only available for Android phones, but the city is working on versions for other systems.
Launched last week, the app has already been downloaded more than 13,000 times -- including more than 100 times in the United States.
Juarez has been working to shed the dark distinction of being one of the world's most dangerous cities for women.
The crisis has eased somewhat since the 1990s, when rights groups estimate that more than 1,500 women were murdered.
The victims were primarily poor young women who had come to the city to work in the "maquila" industry, factories that assemble products to ship across the border.
Many were found raped and brutally tortured, their bodies left in the desert that surrounds the city.
These days, violence in Juarez makes fewer international headlines. It is no longer Mexico's murder capital, and attention has shifted to new hotspots in the country's deadly war on powerful drug cartels.
But the city of 1.4 million people remains a dangerous one for women: 54 were reported missing last year, and 17 have disappeared so far this year.
And city officials have noticed a worrying trend: the victims still tend to be poor young women.
"We are concerned about the disappearance of young women with very similar profiles to those who were disappearing years ago," said Veronica Corchado Espinoza, head of the city government's Women's Institute.
Residents give the app strong reviews: it has four out of five stars in the Google Play store.
"For my daughters who are away from home, at school or where something could happen, it's faster for them to communicate, not just with me but anyone else," Juarez resident Patricia Palma told AFP.
Women's rights activists have also praised the app.
"There is a great need for women to be able to count on these types of tools... to strengthen our networks and send an alert when we are in a potentially dangerous situation," said Itzel Gonzalez of the Women's Network of Juarez.