SAN DIEGO -- The cause of a brush fire that scorched about 100 acres and prompted voluntary evacuations in Sorrento Valley over the weekend was under investigation Monday, authorities said.

The fire was reported around noon Sunday in the Los Penasquitos Preserve near Sorrento Valley Boulevard and was fully contained by around 7:30 p.m., said Maurice Luque of the San Diego Fire-Rescue Department.

The fire was fueled by a combination of high winds, hot temperatures and low humidity -- the same type of hazardous fire conditions that normally occur later in the summer, Luque said.

Residents of about 250 homes in the area were encouraged to evacuate but no structures or people were ultimately harmed in the blaze, which was fought from the air and ground by more than 60 firefighters, Luque said.

Fire investigators are working to determine a cause, Luque said, adding that arson was not immediately suspected.