Caltrans says there are no plans to reopen I-5 north of Redding on Thursday night and will re-evaluate on Friday morning.
VIDEO: 'I might die here': Videos show drivers escaping wildfire on I-5 in Shasta County near Redding
Officials have issued evacuation orders, but did not immediately say how many people are impacted. The fire is in a rural area with scattered homes.
Thousands of people were stuck after it ignited Wednesday just before 1 p.m. There were abandoned trucks destroyed by the flames as the fire jumped I-5.
"It felt like it was coming to us so some of the guys that were in front of us, I don't know like five or ten trucks in front of us were closer to it, they had to drop their trailers and turn around," said Julio Vega, motorist.
VIDEO: Woman grateful to be alive after fleeing Shasta Co. wildfire
The U.S. Forest Service has launched a full aircraft attack and ground response.
Officials say the cause of the fire was human, but they did not go into specifics.
Get the latest stories and videos on wildfires burning across California, here.
PHOTOS: A look at wildfires burning across California