Fire breaks out in Riverside riverbed

RIVERSIDE, Calif. (KABC) -- Firefighters were battling a fire in a riverbed in Riverside Saturday night.

The blaze started at about 2:31 p.m. in the Santa Ana Riverbed near the 2600 block of Fairmount Boulevard, according to the Riverside Fire Department.

Video from the scene showed the flames were burning palm trees and brush. Officials estimated the fire to be between 35 and 40 acres, and 50 percent contained.

Structures were threatened, but no buildings had burned, and there were no evacuations in place, according to the fire department.

Crews were providing structure protection throughout the surrounding neighborhoods.

The cause of the fire was under investigation.