By BILL HUTCHINSON, ABC News

(ASPEN, Colo.) — The FBI has joined a criminal investigation of what police said appears to be an “intentional attack” on gas service lines in Aspen, Colorado, that left thousands of residents and businesses without heat as temperatures in the skiing mecca plunged to near zero degrees.

Work crews are scrambling to restore gas service, and local authorities handed out electric space heaters to residents still without heat Tuesday, as a storm is forecast to bring up to 8 inches of snow in the Rocky Mountains region this week. Temperatures are forecast to fall to 2 degrees in Aspen on Tuesday night, according to the National Weather Service.

Aspen police said the apparently coordinated acts of vandalism occurred Saturday night at three separate Black Hills Energy gas line sites, one in Aspen and two elsewhere in Pitkin County.

At one of the targeted sites, police said they found the words “Earth first” scrawled, and investigators were looking into whether the self-described “radical environmental group” Earth First! was involved.

Emails from ABC News to the group’s website seeking comment were not returned.

Aspen Assistant Police Chief Bill Linn told reporters that the saboteurs appeared to “have some familiarity” with the natural gas system.

“They tampered with flow lines. They turned off gas lines,” Linn said.

Linn said physical evidence recovered at the scenes of the vandalism included footprints left in the snow. He said there were no security cameras at the three locations that were hit.

The FBI, which has a critical infrastructure protection unit, is helping in the investigation, Linn said.

Black Hills Energy officials said about 3,500 customers were affected by the gas outage, and crews had to go to each natural gas meter to manually turn them off and relight the pilot lights. Officials said the work was continuing Tuesday, but it was unclear how long it would take before gas service is restored to everyone.

Linn said the police department was handing out about 6,000 portable space heaters to residents.

He added that numerous businesses, including restaurants and hotels, had to shut down due to the loss of gas.

“It’s almost, to me, an act of terrorism,” Pitkin County Commissioner Patti Clapper, who lost heat in her home due to the vandalism, told The Aspen Times newspaper. “It’s trying to destroy a mountain community at the height of the holiday season. This wasn’t a national gas glitch. This was a purposeful act. Someone is looking to make a statement of some kind.”

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