Behind the cheery smiles of Mickey Mouse and Cinderella, not everything is quite so innocent in Disneyland and the surrounding area of Anaheim, California.

The local Anaheim police force has obtained a cell phone-spying device that was originally devised for major national security investigations, according to documents obtained by the American Civil Liberties Union.

Although it’s not clear exactly when and where the military-grade equipment has been used, documents show Anaheim police have owned such high-tech tools since 2009. Language used in the documents obtained by ACLU, however, suggests that they have indeed been used. For instance, in a document from the Anaheim police (pdf) requesting an “upgrade” to the dirtboxes purchased in fiscal year 2007, the department says:

“Currently, every city in Orange County [in which Anaheim is located] has benefited from the DRT device. Without an upgrade, Orange County as a whole would lose valuable knowledge necessary to investigate terrorism cases and solve crimes.”

A DRT device (or “dirtbox”) works by emitting a similar signal to cellphone towers so that it can connect with cellphones to intercept and store information. And, because they can be mounted on airplanes, dirtboxes can cover large areas to collect information from thousands of phones. Previously, the only known domestic uses of these devices was by the federal government and two major cities, Los Angeles and Chicago, reports the ACLU.

The fact that the surveillance project extends beyond Anaheim to include “every city in Orange County” also suggests the surveillance program could have been swiping data from the cellphones of 3 million OC residents as well as the 16 million tourists who visit Disneyland per year.

And the potential invasion of privacy doesn’t necessarily end there. If the Anaheim police force was given dirtboxes, then it suggests such powerful spying devices could be far more common tools of US policing than previously thought. “If a city of only a few hundred thousand people like Anaheim has purchased this wide array of devices, it begs the question of how widespread these tools really are,” wrote Matt Cagle, technology and civil liberties policy attorney for ACLU.

A spokesperson for Anaheim Police said that, due to ongoing civil litigation, the department could not comment. Quartz has contacted Disneyland Park, California, and will update this post with any comments.