A small grass fire prompted a pre-evacuation notice in Jefferson County on Monday. At about 2:30 p.m. the sheriff’s office announced the fire was about 1/4 of an acre and burning in an area close to Arnett Ranch Road. The neighborhood is southwest of Denver and northwest of Roxborough State Park. At about 2:40 p.m., the sheriff’s office announced air support was being called in and there were no structures threatened at that time. At about 2:50 p.m. the sheriff’s office stated the air support was called off because ground crews were making good progress on the small blaze. At about 3:30 p.m. the pre-evacuation notice was lifted. The sheriff’s office is reporting ground crews had to hike about 500 yards in steep terrain to reach the fire. Lightning is believed to be the cause of the small fire.