Four injured, nearly 1,000 acres burning and 0% containment: Here's what we know about the brush fire tearing through Riverside, California

A raging brush fire has kept Southern California on edge since Tuesday morning. The fire broke out around noon in the dry Santa Ana Riverbed in the Mira Loma neighborhood of Jurupa Valley and, within hours, raged out of control, forcing the evacuation of entire neighborhoods in the neighboring city of Riverside.

The start of the fire was reported at 11:22 a.m. local time at the intersection of Bain Street and Limonite Avenue, just north of the Hidden Valley Nature Center, the Riverside County Fire Department said. Authorities officially dubbed it the "Bain Fire," in reference to the street where it originated. 

The advance was brutal. At 12:36 p.m., the fire covered just 20 acres. An hour and a half later, it had already consumed 250. And according to the latest report from Cal Fire - California's firefighting agency- released around 5:20 p.m., the fire had burned 907 acres with 0% containment. The latter means that not a single stretch of the perimeter was secured by crews, and that the flames could continue to spread freely in any direction.

The same agency confirmed four civilians injured, although it did not specify whether burns, smoke inhalation or another cause caused the injuries. It has not yet been officially reported whether any homes were destroyed, but mandatory evacuation orders were already extended to several areas of Jurupa Valley and Riverside, while other areas of Norco received warnings to be ready to leave at any time. Authorities set up a shelter at the La Sierra Senior Center on La Sierra Avenue and closed Arlington Avenue between Crestview and Western on the Riverside side.

To try to contain the blaze, Cal Fire deployed about 100 personnel, 22 fire engines, two water-dropping helicopters and at least two air tankers, one of which was seen dropping Phos-Chek retardant on the fire. Despite the operation, the fire continued to spread at a "moderate rate" among dense, dry vegetation in the riverbed.

The causes of the fire remain unknown. The area where the blaze started is known for homeless encampments, where waste and open fires, used for cooking or warmth, are common year-round, according to local authorities.

Added to all this is a second active outbreak in the same county. In parallel with the "Bain Fire," the so-called "Verona Fire" near the town of Hemet has already consumed about 200 acres, destroyed outbuildings, and forced the issuance of additional evacuation orders for homes and a mobile home park in the area.