By Jesse Sarles

BOULDER, Colo. (CBS4) – The cause of the Calwood Fire that burned in the Boulder County foothills last year is undetermined.

The wildfire burned more than 10,000 acres to the northwest of Boulder in October, destroyed 26 buildings and forced thousands to evacuate.

READ MORE: Boulder County Seeks More Seasonal Firefighters After Last Year’s Devastating Wildfire Season

Flames from the CalWood Fire (credit: CBS)

The Boulder County Sheriff’s Office had been investigating the fire’s cause along with several other agencies and made the determination official on Wednesday in a news release.

READ MORE: $5.7 Million Secured For Restoration At CalWood Fire Burn Scar

Landowners, neighbors and people who were recreating in the area when the fire first started on Oct. 17 have been interviewed, along with aerial firefighters who were first on scene.

(credit: Goddard family)

The investigation honed the ignition point of the fire down to within a 500 foot radius.

Jesse Sarles