4S RANCH (CBS 8/ CNS) - A brush fire in a creek bed adjacent to Black Mountain Open Space Park blackened about five open acres this afternoon, prompting evacuations of some nearby homes while crews doused the flames by ground and air.

The blaze erupted for unknown reasons shortly before 3 p.m. off the 15000 block of Dove Creek Road in 4S Ranch.

Students at Stone Ranch Elementary sheltered in place, but it was a different story at Oak Valley Middle School.  

Administrators at Oak Valley Middle School had students and staffers remain indoors as the flames spread through thick vegetation in undeveloped ravines and wetland areas a short distance away.

Parents were allowed to pick up there kids, however, parents said the scene was chaotic and the fire evacuation plan needs some work. 

Despite the chaos, or what the district called a "bump in the road," parents were relieved that no one was injured and no structures were damaged.

Nearby residents of homes along Palomino Valley Road were directed to evacuate as a precaution, but were allowed back into their homes soon after 5 p.m., according to Julie Taber, spokeswoman for the Rancho Santa Fe Fire Protection District.

Firefighters surrounded and hosed down the blaze on foot while a helicopter crew used a nearby pond to get water to drop from above.

The Rancho Sante Fe Fire Protection District said they believe the brush fire was an accident caused by welders in the area but it's still under investigation.