Just after noon on October 21, 2007 arcing power lines whipped by Santa Ana winds started a small fire east of Ramona, in the Witch Creek area. By four o'clock the next morning, the Witch Creek Fire had made its way to the San Diego City limits. The Guejito Fire started in the San Pasqual Valley at two o'clock on the morning of October 22. It wasn't long before the two fires merged.

More than 197,990 acres of San Diego County burned in the fires, 9,250 acres within the City of San Diego. 365 residences were destroyed in the City, all of them in the Rancho Bernardo community. Countywide, 1141 residences were destroyed. Two people died in the county.

The fires triggered the largest evacuation in county history. More than 500,000 people lived in the areas evacuated, 200,000 of them within the city.

At the height of the fire, San Diego Fire-Rescue Department had 73 engines, 7 trucks and 420 people deployed.

The Witch Creek and Guejito Fires were among 21 wildfires burning in Southern California. The Harris Fire in southern San Diego County started the same day as the Witch Creek Fire. It grew to 90,440 acres but did not enter the city. There were five deaths in the Harris Fire.