IDYLLWILD (CBSLA) – A fast-growing wildfire in the rural Riverside County community of Idyllwild in the San Jacinto Mountains has forced evacuations Wednesday afternoon.

The Cranston Fire broke out sometime before noon off Highway 74, between Hemet and Mountain Center. By Wednesday night, the fire had grown to about 4,700 acres and was five percent contained, the U.S. Forest Service reports.

Mandatory evacuations had been issued for Idyllwild, Pine Cove and Fern Valley.

As of 4 p.m. 110 homes had been evacuated, 600 structures were threatened and 3,800 customers in the Idyllwild area were without power, according to the U.S. Forest Service.

A total of 500 firefighters were on scene with 55 engines, eight crews, nine dozers, five water tenders, one VLAT, 10 tankers, six helicopters and nine fixed wings.

The name of the suspected arsonist is Brandon N. McGlover, 32, of Temecula, according to the USFS. CAL Fire law enforcement officers arrested McGlover and booked him on five counts of arson to wildland.

Evacuations are ordered at Inspiration Point moving East along Double View all the way to HWY 243. IFPD – FF https://t.co/I779pfOn6k — Idyllwild Emergency (@IdyllEmergency) July 25, 2018

The fire was growing at a “rapid rate of spread,” the San Bernardino National Forest tweeted.

Highway 74 between the Cranston Fire Station and Lake Hemet was closed. Highway 243 between Pine Cove and Mountain Center was also closed.

Firefighters were CAL Fire and USFS were battling the blaze.

The cause of the fire was not known.