PHILADELPHIA - Police have arrested a 20-year-old man after they say he flew a drone within feet of a police helicopter flying around downtown Philadelphia.

Chief Inspector Scott Small says the unmanned aircraft was first spotted around 6 p.m. Wednesday in an area where roughly 300 demonstrators were engaging in an anti-Donald Trump protest.

The police helicopter was monitoring the protest below when the drone came within several feet of it.

Police tracked the drone to a nearby building that houses students from multiple local colleges and arrested its operator. He was charged with reckless endangerment.

The case has been passed along to the Philadelphia District Attorney's Office. Additional charges for the unnamed suspect are possible.