Updated 7:50 p.m.
The Bernardo Fire, sparked earlier this week during construction on a housing project near Rancho Bernardo, is now completely contained, authorities reported Saturday evening.
The first wildfire to erupt in San Diego County this week blackened nearly 1,600 acres between Rancho Penasquitos and Rancho Santa Fe, prompting the evacuation of about 20,000 households.
However, it did not cause structural damage or serious injuries, according to Cal Fire.
The blaze began at 11 a.m. Tuesday off Nighthawk Lane in 4S Ranch amid hot, dry and gusty conditions and was pushed to the west and north by stiff Santa Ana winds.
Investigators determined that the Bernardo Fire began as a crew was excavating trenches to test soil at the work site near Del Norte High School.
After digging and then covering one of the troughs, they started moving to the next excavation location, according to the San Diego Fire-Rescue Department. They then noticed flames spreading rapidly through dry brush and tried in vain to extinguish them before fleeing for their own safety, officials said.
— City News Service