The fire, which charred 115 acres, initially threatened homes, which prompted mandatory evacuations. All evacuations were lifted by Tuesday morning.
The Lake Fire was reported around 11:10 a.m. in the area of Jurupa Avenue and Van Buren Boulevard, less than a mile north of Riverside Municipal Airport, according to the Riverside County Fire Department.
Additional fire information:
On Monday afternoon, crews established tentative containment lines, and all spot fires outside of the main blaze were knocked down, multiple engines, truck and hand crews from the county, city of Riverside, Corona and Murrieta Fire & Rescue converged on the location and encountered flames moving at a moderate rate eastward through thick vegetation.
At 12:40 p.m., the blaze turned north, immediately threatening properties near Kennedy Street and Riverdale Place in Jurupa Valley. Sheriff's deputies were summoned to initiate mandatory evacuations in the neighborhood.
Two Cal Fire water-dropping helicopters made a series of runs that slowed the fire's progress, allowing crews to form protective lines around the homes.
A battalion chief at the scene described the winds as "erratic," hampering containment efforts.
The cause of the fire was not immediately known.
The river bottom is dotted with homeless encampments, and during dry periods, fires from camping and cooking are a regular occurrence.
No injuries were reported.