The South Fork fire, which has destroyed more than 17,000 acres near Ruidoso, New Mexico, was caused by a lightning strike, Bureau of Indian Affairs officials said.

An investigation conducted by wildland fire and law enforcement determined human activity did not start the South Fork Fire, Bureau of Indian Affairs officials said Wednesday, July 3. The cause of the fire was uncovered through a “thorough investigation by multiple agencies, including the Bureau of Indian Affairs, U.S. Department of Agriculture Forest Service and the FBI,” officials said.

The South Fork Fire started June 17 near Ruidoso on tribal trust land administered by the Bureau of Indian Affairs Mescalero Agency. The South Fork Fire has destroyed 17,569 acres of land as of Wednesday, July 3, Southwest Area Incident Management Team officials said. The fire containment is now at 87%, officials said.

The South Fork Fire destroyed more than 15,000 acres within the first 24 hours due to high winds, officials said.

Cause of Salt Fire near Ruidoso remains under investigation

While the cause of the South Fork wildfire is now known, the Salt Fire near Ruidoso remains under investigation, officials said.

The FBI is still offering a $10,000 reward to anyone who can provide information leading to the arrests and convictions of the person or people responsible for starting the Salt Fire, officials said.

Anyone with information about the cause of the fires is asked to call the FBI at 1-800-225-5324 or submit the information online at tips.fbi.gov. People can also text “BIAMMU” to 847411 then “MESCALERO FIRE + the tip” or just BIAMMU to 847411 and the tip.

The Salt Fire has destroyed about 7,939 acres of land as of Wednesday, July 3, Southwest Area Incident Management Team officials said. The fire containment is now at 84%.

Two people have died in the South Fork and Salt fires, which displaced more than 8,000 people.

No further information has been released.

Aaron Martinez may be reached at amartinez1@elpasotimes.com or on Twitter @AMartinezEPT.