Story highlights

NEW: The fire is estimated at 5,000 acres, up from 300 earlier

Some 450 firefighters are working the blaze, located in Riverside County

(CNN) —  

A fast-moving wildfire in Southern California is threatening homes and has prompted evacuations.

The fire, which was reported Wednesday, jumped from approximately 300 acres to 5,000 acres, according to Capt. Lucas Spelman with the California Department of Forestry and Fire Protection.

Some 450 firefighters are working the blaze, which is located in Riverside County.

Mandatory evacuations are in effect for the communities of Vista Grande, Mt. Edna, Poppet Flats, Twin Pines and Silent Valley, according to Riverside County Fire Department officials.

It was not immediately clear how many people are affected.

An evacuation center was set up at an area high school.

CNN’s Diahann Reyes contributed to this report.