BALTIMORE (AP) — The Federal Aviation Administration said Friday that it will investigate after a drone briefly delayed the Ravens-Bengals game in Baltimore on Thursday night.

Drones are barred from flying within 3 miles (5 kilometers) of stadiums that seat at least 30,000 people during events including National Football League and Major League Baseball games, and in the hour before they start and after they end, according to the FAA. The agency looks into all reports of unauthorized drone operations and investigates when appropriate, it said in a statement.

When the drone violated the FAA’s temporary flight restriction on Thursday night, the Maryland Stadium Authority said Maryland State Police and authority officials found the operator, who was directed to immediately land the drone. The operator was unaware of the restrictions and did not have a waiver to operate the drone in stadium airspace during the game, the authority said in a statement.

The authority said that in 2021, it installed drone detecting and deterring technologies, as well as signs reminding fans that it is a “No Drone Zone.” Stopping play while a drone is above a stadium’s seating is an NFL security requirement, it said.

“We saw them up there, drones. That’s a first,” Ravens coach John Harbaugh said. “I thought I’d seen it all with the Super Bowl, the lights going out at the Super Bowl. Now we got drones flying around.”

The lights went out during Baltimore’s victory over San Francisco in the Super Bowl in New Orleans after the 2012 season.

Drone operators who conduct unsafe operations that endanger other aircraft or people on the ground could face fines that exceed $30,000 or have their drone operators’ pilot certificates suspended or revoked, according to the FAA.