Gas Line Explosion Near Castaic Shut Down I-5 on Saturday, Cause Under Investigation

A gas line explosion shortly after 4:00 p.m. Saturday prompted sweeping freeway closures and shelter-in-place orders across parts of Castaic, causing significant travel delays in Ventura and Los Angeles counties, according to authorities.

The California Highway Patrol issued a Sigalert at 5:03 p.m., closing all northbound and southbound lanes of Interstate 5 between the Lake Hughes Road and Lower Crossover exits. Northbound traffic was diverted to Highway 126 and southbound traffic to State Route 138.

CHP lifted the closure for both directions at 8:44 p.m.; by late Saturday evening, northbound I-5 had reopened at SR-126 and southbound I-5 at SR-138 shortly after.

The Los Angeles County Fire Department issued a critical shelter-in-place order at 5:40 p.m. for the CAS-SLOAN area—bounded by the Ninetynine Oaks community to the south, the Castaic Town Center to the north, Interstate 5 to the west, and Sloan Canyon Road to the east. Additional shelter-in-place orders were issued around 6:45 p.m. in the Stonegate neighborhood, east of I-5 between Ridge Route Road and Castaic Road.

The Santa Clarita Valley Sheriff’s Station said the explosion was likely caused by a natural gas line and remains under investigation. Reports from the scene indicated gas service in the immediate area was shut off Saturday night.

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

Initial reports placed the blast near the 3200 block of Ridge Route Road, though that location remains tentative. Dispatch logs and the PulsePoint app showed L.A. County Fire units responding to North Ridge Route Road and Pine Crest Place at 4:17 p.m.; CHP received the first call at 4:19 p.m. about a possible gas pipe explosion.

Residents as far away as Westridge in Valencia and Stevenson Ranch reported smelling natural gas following the incident. It was not immediately clear whether there were any injuries.