Authorities say a drone came within about 100 feet (30 meters) of a state police helicopter in Massachusetts.

A state police spokesman says the helicopter was passing over Lawrence Municipal Airport at approximately 600 feet (183 meters) late Wednesday morning when the crew spotted the drone approach from the side.

The drone flew in front of the helicopter before suddenly dropping to the ground. Police say if the drone had struck the plane's windshield, it could have entered the flight cabin.

The helicopter as well as cruisers on the ground unsuccessfully searched for the person flying the drone.

The helicopter landed safely.

Police say it's illegal to operate drones within 5 miles of an airport or higher than 400 feet (122 meters).

State police are investigating.