Two incidents involving drones hindered aerial firefighting this week as emergency responders continued to battle a raging 23,199-acre wildfire in California's San Bernardino mountains, officials said.
The drones flew into the airspace over the blaze, and fire officials immediately grounded firefighting aircraft to ensure pilot safety, according to a statement from Southern California Interagency Incident Management.
"Losing the ability to utilize these aircraft has a serious impact on the success of the firefighters on the ground," said the incident team, which has been fighting the massive fire since it was reported June 17.
The California Department of Forestry and Fire Protection followed up with its own warning on Friday: "A collision with a hobby drone could easily result in major damage to firefighting aircraft, injuries to the pilot and crew on board as well as firefighters below, and worse, a midair collision."
CalFire said it wants "to stress to hobby drone users: 'If you fly, we can't!"
A source familiar with the incident told NBC News' Andrew Blankstein that the Federal Aviation Administration is "aware of the incident and looking into it."