A police dog sniffed lockers at Bel Air Middle School on Friday as part of the school system's effort to keep illegal drugs out of schools—but no illegal substances were found in the search.

The scan by the drug dog was a routine, random scan conducted by four Harford County sheriff's deputies, the police dog, two school administrators and the school system's coordinator of safety and security, according to a release from Harford County Public Schools.

Between 1:05 and 1:20 p.m., the dog checked 360 lockers and did not detect any controlled dangerous substances or tobacco, according to the school system.