Two people were killed when two airplanes that were battling a 500-acre fire collided in the air Thursday.

The midair crash between two single-engine air tankers contracted by the Department of the Interior happened shortly before 1 p.m, the Reno Gazette Journal reports. The Bureau of Land Management told the news outlet that the planes went down near the Bishop Fire, nearly 20 miles southwest of Caliente.

The planes were deployed to help wildland firefighters on the ground contain the Bishop Fire. They would drop 800 gallons of fire retardant to areas that large air tankers cannot access.

Only one pilot was aboard each plane. The identity of the pilots has not been released.

“We offer our sincere condolences to the families of the two pilots and to all those working with the BLM Nevada Ely District,” BLM Nevada State Director Jon Raby told the Gazette Journal.