An Apple AirTag was found hidden underneath the hood of a marked NYPD car in Queens, police sources said Monday.

The coin-sized tracking device, which connects to Apple’s “Find My” network, was discovered on the police car Sunday. The AirTag had been placed in a small plastic baggie.

The finding prompted NYPD Chief of Housing Martine Materasso to remind members of the department to be vigilant in their inspections of marked cars, which are supposed to be done before and after their tours, the New York Daily News reports.

“Please keep a heightened state of vigilance, in light of the anti-police sentiment we have seen not only here, but across the U.S.,” Materasso wrote in the email sent out to officers. “Continue looking out for each other and be safe.”