Firefighters worked Monday evening to hold a brush fire in Castaic that had shut down lanes of Interstate 5 and put a mobile home community on notice to be ready to leave, a fast-moving but limited blaze on the northern edge of Los Angeles County.

What is burning, and where

The blaze, named the Martin Fire, broke out near Templin Highway and the northbound 5 Freeway, ABC7 reported. Officials said it began when flames from a vehicle fire spread into nearby brush. The Los Angeles County Fire Department and personnel from the Angeles National Forest responded.

As of about 6:20 p.m., the fire had burned roughly 25 acres and was about 46 percent contained, ABC7 reported; an earlier report had put it at about 15 acres, an indication of how quickly it grew before crews gained ground. Figures on an active fire change quickly.

Freeway closures

The fire snarled one of the region's main north-south arteries. Multiple northbound lanes of the 5 Freeway were closed and a Sigalert was issued as traffic backed up, ABC7 reported. Drivers were urged to expect delays through the Castaic area.

Evacuation warning, not an order

Authorities issued an evacuation warning, a step short of a mandatory order, for the Paradise Ranch Estates Mobile Home Park, covering about 133 homes, ABC7 reported. NBC Los Angeles reported that the warning applied to the zone designated CAS-PARADISERANCH. Fire engines were sent to the park as a precaution. A warning tells residents to be prepared to leave; an order tells them to go.

No injuries reported

No injuries had been reported as of Monday evening, according to ABC7. Crews expected to keep working the fire into the night. As with any active incident, the acreage, containment and evacuation status could change, and residents in the area were advised to follow guidance from Los Angeles County and fire officials.