LOS ANGELES (KTLA) – Firefighters on the ground and in the air rushed to slow a rapidly spreading brush fire that exploded near Castaic on Wednesday, forcing tens of thousands of evacuations and impacting traffic on the 5 Freeway.

The Hughes Fire erupted around 10:50 a.m. in the area of Lake Hughes Road east of Castaic Lake, according to Cal Fire incident commanders.

It spread quickly through dry brush and trees, fanned by strong Santa Ana winds. The fire was initially reported at 50 acres but had exploded to over 9,400 acres by 5 p.m., according to CalFire, with no containment.

The cause of the fire was unknown.

Officials told KTLA 5 News that roughly 31,000 people, including residents of Castaic, were being evacuated from communities south, north and west of the wildfire. At about 2 p.m., a portion of Ventura County near Lake Piru was added to the mandatory evacuation zones.

About 23,000 more were under evacuation warnings, including residents of Ventura County south of Lake Piru.

Included in the evacuation zone were several schools including Northlake Elementary, Castaic Middle, Castaic Elementary and Castaic High. A temporary evacuation center was set up at Hart High School, 24825 Newhall Ave., Santa Clarita, CA 91321.

All students evacuated safely, officials said. The Castaic Union School District and Saugus Union School District have canceled classes for Thursday.

At least one L.A. County detention facility was evacuated, moving some 400 people being held at the location, L.A. County Sheriff Robert Luna said at a Wednesday night press conference.

Luna assured evacuated residents that deputies were on patrol to prevent any looting or crime.

As a result of the blaze, the 5 Freeway was temporarily closed between the 126 Freeway and Grapevine Road, though the California Highway Patrol reopened the roadway Wednesday evening so residents and first responders can get in and out of the area.

The following closures, according to CHP, will remain in place:

• I-5 northbound to Parker Road offramp
• I-5 northbound to Lake Hughes Road offramp
• Parker Road and Ridge Road eastbound from The Old Road
• Lake Hughes Road eastbound from The Old Road

“If you can, just avoid the area,” CHP spokesperson Alec Pereyda added.

“State resources have been deployed to the Hughes Fire in the Angeles National Forest to assist in the federal response,” California Gov. Gavin Newsom posted on social media. “We will continue to monitor the situation closely and provide the federal government with whatever it needs to extinguish this fire.”

Smoke from the fire is creating extremely hazardous air quality conditions in the area including the San Gabriel Mountains, the I-5 corridor near Castaic Lake, Santa Clarita and communities south and west through Ventura County.

L.A. County Fire Department Chief Anthony Marrone said fire personnel staffing will remain high as local, out-of-state and international crews work overnight to contain the blaze.

Will Conybeare and Marc Sternfield contributed to this report.