That suspicious guy on your morning train commute isn't the only thing you should be worried about—at least according to a class action filed Monday that claims the Bay Area Rapid Transit, or BART, is illegally collecting the cell phone numbers, names and locations of its riders.

The suit, filed in federal court in Oakland, California, by lawyers with Edelson PC, alleges that a mobile Google application called “BART Watch” allows the transit agency to track its riders. BART launched the app, which is designed to alert law enforcement of suspicious behavior, in 2014.

“Through their BART Watch mobile application available for free download in the Google Play store, defendants have convinced tens-of-thousands of Californians to download the app to keep up with transit alerts, report incidents (anonymously or not), and to call the BART police with a press of a button,” the complaint says. “However, a detailed review of the BART Watch app reveals that defendants have been using it secretly to collect Californians' unique mobile device identification numbers … and to periodically track their precise locations.”