Arson investigation opened as crews contain Oak fire in Littleton

This post was updated at 1:50 p.m. on Tuesday.

The Jefferson County Sheriff’s Office on Tuesday said it found evidence that suggests someone deliberately ignited the fast-moving Oak fire.

Jacki Kelley, a spokesperson for the office, declined to give details on how the fire started or who might be responsible but said authorities were investigating the fire as a possible arson.

Our original story follows below.

Crews worked Monday to contain a fast-moving grass fire that ignited near Chatfield State Park in Littleton. Fire officials say strong, unpredictable winds fueled its rapid growth to about 150 acres.

A small air tanker was used to help fight the blaze, dubbed the Oak fire, which stopped just a few feet from the Westerly Apartments in Littleton.

"We were playing a board game and then we got a knock on our door," said resident Abby Nieskes. "It was a police officer saying there was a big fire and to evacuate — pack up a bag of stuff and leave." 

The Jefferson County Sheriff's Office issued mandatory evacuation orders for the apartment complex and residents in nearby Ken Caryl Valley but canceled them around sunset after winds died down and crews got better control of the fire.

It's unclear what caused the fire. No injuries or major damage have been reported.

Late-December wildfires aren’t unprecedented in Colorado, but scientists and fire ecologists say climate change, fueled largely by human-made carbon emissions, is leading to warmer temperatures, more intense droughts and longer fire seasons that extend into winter months.