LA CUEVA, N.M. (AP) — The Latest on a wildfire burning in New Mexico's Jemez Mountains (all times local):

6:30 p.m.

A fire burning in northern New Mexico has charred about 600 acres so far and forced the evacuation of about 200 people.

Santa Fe National Forest spokeswoman Julie Anne Overton says the cause of the fire first reported Thursday morning is under investigation.

She says the blaze is the Jemez Mountains west of Los Alamos and about 300 structures could be at risk.

The fire is about 20 miles away from Los Alamos and burn scars from previous fires in the area may keep it from hitting the city.

Overton says about 100 firefighters are on the scene along with three heavy air tankers, six engines and a helicopter with more ground crews arriving by Friday.

Gov. Susana Martinez has activated the state emergency operations center to help with a coordinated response to the fire.

4:10 p.m.

Gov. Susana Martinez says as many as 200 people have been evacuated as a precaution due to a fire burning in northern New Mexico.

The governor has activated the state emergency operations center to help with a coordinated response to the fire.

The blaze was first reported Thursday morning and quickly spread to more than 100 acres.

Sheriff's deputies initiated evacuations and closed a stretch of New Mexico Highway 4 between Los Alamos and the mountain village of La Cueva.

Visitors were also evacuated from the Valles Caldera National Preserve.

The fire was burning near the boundary of the preserve and the Santa Fe National Forest. Officials say structures were threatened but they could not say how many.

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3:20 p.m.

Federal forest officials say they have yet to determine how many homes and summer cabins are being threatened by a blaze burning in northern New Mexico.

The fire was reported Thursday morning and quickly spread to an estimated 100 acres near the boundary of the Santa Fe National Forest and the Valles Caldera National Preserve.

Officials say the fire was spreading and moving to the east.

The fire produced a plume of smoke that could be seen for miles.

Several engines, three air tankers and a helicopter were assigned to the fire, and forest officials said more resources were ordered.

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2:40 p.m.

Federal forest officials say they're not sure what sparked a blaze that has forced evacuations and is sending up a large plume of smoke in northern New Mexico.

Sandoval County authorities initially reported that the fire was a controlled burn in the Jemez Mountains that got out of control.

Officials with the Santa Fe National Forest say no federal or state agency is conducting any controlled burn during the fire season.

Forest spokeswoman Julie Ann Overton says structures are threatened by the flames but she's unsure of how many homes are in the area and how many people were evacuated.

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1:50 p.m.

Authorities have closed New Mexico Highway 4 to help with the evacuation of residents in the Jemez Mountains due to a wildfire.

The highway is closed on the east end at Los Alamos and on the west end at the mountain community of La Cueva.

Sandoval County Sheriff's Lt. Keith Elder says deputies are working to evacuate residents from the Ruby Hole subdivision. He says the flames have cross the highway and he's unsure of how many homes are in the area.

Elder says the fire was initially a controlled burn that got out of control. By Thursday afternoon, the plume could be seen as far away as Albuquerque.

Several fires are burning around New Mexico but most are in more remote areas. The Jemez Mountains are dotted with pockets of homes and summer cabins.

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12:47 p.m.

New Mexico authorities are initiating evacuations in an area of the Jemez Mountains after a prescribed fire grew out of control.

Sandoval County Sheriff's Lt. Keith Elder says deputies are working to evacuate residents from the Ruby Hole subdivision along State Highway 4. Elder said he did not know how many homes were in the area.

He says the flames have cross the highway and it will be closed to keep people out of the burn area.

The fire was initially reported at only 2 acres, but by Thursday afternoon the plume had grown significantly and could be seen from communities that were miles away.

Several fires are burning around New Mexico but most are in more remote areas. The Jemez Mountains are dotted with pockets of homes and summer cabins.