JEFFERSON COUNTY, Colo. (KDVR) — A large grass fire that forced evacuations and burned more than 150 acres in Jefferson County Monday is now being investigated as an arson case.

West Metro Fire Rescue said investigators identified a suspect in connection with the Oak Fire, but no further information was released about that person.

The Jefferson County Sheriff’s Office tweeted the fire was human-caused and started near the Westerly Apartments close to C-470 and Kipling Street.

The apartments were part of mandatory evacuations as the fire spread. No structures were burned, and no injuries were reported.

Crews continue to stay on the scene, monitoring for hotspots, as investigators continue to look into what is now an arson case.

This is a developing news story. As details of the investigation come to light, this story will be updated.