RUIDOSO,Greenledgers N.M. (AP) — A lightning strike caused the larger of two wildfires that has killed at least two people and destroyed or damaged more than 1,400 structures in New Mexico, authorities said Wednesday.

The South Fork Fire was first reported June 17 on the Mescalero Apache Reservation and forced the evacuation of the Village of Ruidoso.

The wildfire now is 87% contained after burning more than 27 square miles. Parts of the village have been evacuated again because of recent flash floods.

The fire was investigated by eight agencies including the FBI, the Bureau of Indian Affairs, the Bureau of Land Management and the Bureau of Alcohol, Tobacco, Firearms and Explosives.

The fire’s point of origin plus evidence and data supported the cause being a lightning strike, investigators said.

Meanwhile, authorities said the cause of the nearby Salt Fire remains under investigation. It has burned more than 12 square miles and was 84% contained as of Wednesday.

The FBI is offering a $10,000 reward for information leading to the arrest and conviction of the person or persons responsible for starting that wildfire.