BELLVUE, COLO. (AP) -- Helicopters and ground crews are trying to extinguish a 100-acre spot fire that ignited ahead of an 81-square-mile blaze in northern Colorado.

Incident commander Bill Hahnenberg said Friday 100 hotshot ground firefighters are at the spot fire, which erupted on the north side of the Poudre (POO'dur) River.

The Larimer County Sheriff's Department says at least 48 homes are confirmed to have been damaged or destroyed since the fire began a week ago, and the number is expected to go higher.

The fire is 15 percent contained and has cost about $7.2 million to fight

Evacuation calls have been made to about 3,000 phones, but authorities cannot say how many homes are involved. Evacuation orders have been lifted for about 1,200 of those numbers.

The fire was caused by lightning.

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