RUIDOSO, N.M. – Wildland fire and law enforcement investigators have determined that the cause of the South Fork Fire was a lightning strike.

The fire was first reported on June 17 on the Mescalero Apache Reservation near Ruidoso. Despite a quick response by multiple agencies, the fire spread to over 15,000 acres within the first 24 hours due to high wind.

As of Wednesday, the fire is at 17,569 acres and 87% contained.

The investigation was conducted by wildland fire investigators and law enforcement officers from the Bureau of Indian Affairs, Office of Justice Services, Bureau of Land Management, U.S.D.A. Forest Service, Mescalero Conservation Law Enforcement Department, Bureau of Alcohol, Tobacco, Firearms and Explosives, New Mexico State Parks, and the Federal Bureau of Investigation.

The cause of the nearby Salt Fire remains under investigation. The FBI is offering a $10,000 reward for information leading to the arrest and conviction of the person or persons responsible for starting the Salt Fire. Anyone with information is encouraged to call 1-800-CALL-FBI, or text an anonymous tip to “BIAMMU” (mobile number 847411). Tips may also be submitted online at tips.fbi.gov.