High-Pressure NatGas Line Ruptures Outside Los Angeles, Forcing Major Highway Shutdown

A rupture of a high-pressure 34-inch natural gas transmission line late Saturday afternoon forced the temporary closure of Interstate 5 north of Los Angeles for several hours and led to a shelter-in-place order for thousands of residents in Castaic.

Capt. Brian Knight, a spokesman for L.A. County Fire, told ABC News that a loud blast was reported around 4:20 p.m. local time. Knight said there were no reports of any injuries.

BREAKING: A massive 36-inch underground natural gas pipeline rupture sent high-pressure gas spewing into the air across the Santa Clarita Valley moments ago, prompting emergency evacuations and shelter-in-place orders in the Castaic area.

The rupture was reported shortly before… pic.twitter.com/37GsIfx9fI

— Austin Dave (@AustinDave_) December 28, 2025

WATCH: Loud booms heard as major gas line explosion triggers shelter-in-place in Castaic, California https://t.co/7pHnuSxNVu pic.twitter.com/0Xf8jcviAe

— Rapid Report (@RapidReport2025) December 28, 2025

The damaged line was identified as a 34-inch, 600-psi transmission pipeline that released NatGas into the air and led to a shelter-in-place order for 14,900 people across the Charley Canyon, Hillcrest, and Wayside communities.

The northbound and southbound lanes of Interstate 5 were closed due to the leak, sparking traffic mayhem across the area.

Drivers were stranded on the 5 Freeway on Saturday night after a natural gas leak in Castaic left all northbound and southbound lanes shut down. The gas has since been shut off, but a shelter-in-place was issued for nearby residences, including the Charley Canyon, Hilcrest and… pic.twitter.com/05KVc81fU1

— ABC7 Eyewitness News (@ABC7) December 28, 2025

It is unclear what caused the NatGas line to rupture. Officials believe a mudslide could be the cause.

A SoCalGas spokesperson told CBS LA that “the cause of the break has not been determined. However, significant land movement has been observed near the break,” adding there were “no indications” of an ignition or explosion.

The transmission line is used for transportation and will not affect service to homes or businesses in the Los Angeles area.