The Federal Aviation Administration issued a warning to drone operators.
"Operating drones around airplanes and helicopters is dangerous and illegal. Unauthorized operators may be subject to stiff fines and criminal charges, including possible jail time," the agency said.
The FAA sent out this message Wednesday as the number of close calls with unmanned aircrafts reported by pilots soared by 762.5 percent in June compared with June 2014 and surged by 280.5 percent in July from a year ago.
The agency said firefighters across the U.S. have had to ground their air operations "on several occasions" after spotting one or more drones near a fire.
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"The FAA will continue to work closely with industry partners through the 'Know Before You Fly' campaign to educate unmanned aircraft users about where they can operate within the rules," the agency said.
"However, the FAA also is working closely with the law enforcement community to identify and investigate unauthorized unmanned aircraft operations. The FAA has levied civil penalties for a number of unauthorized flights in various parts of the country, and has dozens of open enforcement cases."