A wildfire forced the evacuation of two small towns as it burned across 10,000 acres of grass and ponderosa pine trees in northeastern New Mexico, authorities said.

Firefighters battling the blaze were helped by calmer weather overnight, state Forestry Division spokesman Dan Ware said Thursday. The fire was first spotted Wednesday on ranch land 11 miles north of Mora, and then moved into ponderosa pine, jumping from tree top to tree top.

A shelter was set up at the Mora High School gymnasium for evacuees from Ojo Feliz, Los Hueros and the ranches, Ware said. He did not know how many people or homes were evacuated but said one structure had been destroyed.

Investigators were trying to determine what sparked the fire, Ware said.