With the temperature of the unstable tank rising, crews are working to determine if the toxic chemical is still a liquid or if it has solidified.
In an update on Saturday afternoon, Orange County Fire Authority said the unstable tank at the GKN Aerospace facility in Garden Grove remains extremely hot, and crews are working around the clock to stabilize the situation.
OCFA Chief Craig Covey called this a "worst-case scenario," the worst he has faced in his 32-year career.
Authorities are warning that the threat of a leak or explosion still appears imminent at this time.
GKN Aerospace revealed that the temperature of the tank was rising by about one degree per hour, and not decreasing as hoped.
The temperature actually increased to 90 degrees from the 77 degrees it was on Friday morning, officials said.
OCFA has been bringing in people from all over the country to help tackle the situation from all angles.
"Think about an ice cube, right? When you freeze water, it starts from the outside in, until the end is solid. That's what's going on here. Have we slowed down that chemical reaction enough that it is slowly curing and losing its intensity to be able to blow up? The question that goes with that is, when it does that, it's pressurizing," Covey said.
Covey described it as a one-inch steel tank. He said experts are trying to find technology, possibly radar, that can see through the tank to detect the status of the liquid inside.
For now, crews are still working to determine if the chemical has solidifed or not.
GKN Aerospace posted a statement on its website on Saturday, saying the team is fully focused on working with emergency services and specialized teams to ensure everyone's safety.
They also apologized to residents and businesses who've had to evacuate and thanked Orange County Emergency Services for their assistance.