A brush fire that broke out Monday in the Santa Ana River bottom in Jurupa Valley spawned multiple spot blazes, burning about 20 acres before crews established tentative containment lines.
The initial non-injury blaze was reported at 1:33 p.m. in the area of Bain Street and Limonite Avenue, according to the Riverside County Fire Department.
The agency said multiple engine and hand crews were sent to the location and encountered flames moving at a slow rate through heavy vegetation.
The main fire led to two or three spot blazes offset from the point of origin, but two Cal Fire water-dropping helicopters stopped the smaller fires from progressing, according to officials.
The thick vegetation posed challenges for fire personnel, but as of 5 p.m. Monday, they had established hose lays, partially encircling the burn zone, according to reports from the scene.
No homes or other structures were threatened.
Winds were light and variable in the Riverside metropolitan area Monday afternoon.
There was no word on what might have triggered the brusher. The river bottom is replete with homeless encampments, and cooking, warming and debris fires cause year-round impacts.