State military officials say the MQ-9 Reaper had taken off from the airfield at Fort Drum and was operating in approved airspace over the eastern side of the lake when it was lost at about 1 p.m. They say the aircraft was not armed. There have been no reports of injuries.

The drone is used by the Air Guard’s Syracuse-based 174th Attack Wing to train Air Force pilots who use it on surveillance and attack missions globally.

The U.S. Coast Guard and local authorities were helping Fort Drum emergency crews searching for the Reaper.

The cause of the crash will be investigated.

Technical and pilot errors were blamed for a Reaper crash in Nevada last year.