COLLEGE STATION, Texas (AP) — State fire officials say a drone being operated near a wildfire southwest of Fort Worth hampered firefighting efforts by forcing aircraft carrying retardant to be grounded.

The Texas A&M Forest Service says two air tankers were grounded Thursday in Erath County when the drone appeared at the wildfire’s perimeter.

Officials say one aircraft had dropped retardant on flames and the second plane was following to drop as well when the drone flew into its path, nearly causing a collision.

The forest service on Thursday responded to 10 separate fires in Texas covering more than 7,000 acres.

Authorities in other states have reported similar problems with drones.

For instance, aircraft fighting two fires in 2015 in California’s San Bernardino National Forest were forced to land when unauthorized drones disrupted operations.