The failing chemical tank in Southern California that caused tens of thousands of people to evacuate is no longer presenting a threat of catastrophic explosion, according to officials.

The temperature is declining within the chemical tank at an aerospace facility in Garden Grove, California, about 30 miles south of Los Angeles, eliminating concerns that the tank could explode and cause of a catastrophic fireball, local authorities said on Monday morning.

“We are happy to report that the threat of a BLEVE [Boiling Liquid Expanding Vapor Explosion] is now off the table,” Orange County Fire Authority (OCFA) Interim Chief TJ McGovern said during an update. “That threat has been eliminated.”

The crisis is not fully averted, McGovern told reporters during a press conference on Monday. But if an explosion or leak were to occur, it would be significantly smaller than the initial worst-case scenario, he said.

Since the temperature inside the tank has decreased, it has allowed the chemical inside to solidify, but it is unclear how much, according to McGovern.

The evacuation orders remain, OCFA Division Chief Craig Covey noted.

“We want to be clear that the evacuation zones are still in play,” he said. “Please abide by those evacuation zones.”

On Thursday, a chemical tank filled with toxic chemicals at GKN Aerospace, a manufacturing company that builds engines and landing gear for both commercial and military aircraft, was showing signs of overheating, which could cause it to overheat or spill, officials said.

The 34,000-gallon tank contained methyl methacrylate, an industrial chemical used in plastic manufacturing, according to the OCFA. The chemical is primarily a respiratory irritant. Short-term exposure can cause skin and eye irritation, as well as breathing problems, according to the EPA.

The “unprecedented” situation caused officials to order about 50,000 people in the vicinity to evacuate in case a leak sent toxic fumes wafting through the neighborhood or cause an explosion could result in a dangerous fireball. California Gov. Gavin Newsom issued a state of emergency in Orange County in response to the incident.

Authorities then worked to cool down the bulging tank to prevent it from exploding. The crack in the tank discovered by firefighters on late Saturday relieved some of the pressure within the tank, Covey said.

While officials were confident that the crack wouldn’t lead to any chemical leaks, they continued to monitor air quality in the region.

Any areas outside of the roughly 10-square-mile evacuation zone “are currently considered completely safe and day-to-day activities can continue as normal,” the OCFA said in an update Sunday afternoon.

Within the zone are schools, hospitals, nursing homes, fire and law enforcement stations and critical infrastructure. Multiple roads were also closed in the area.

“We appreciate your support and the patience while we work through this incident together,” Covey said.

ABC News’ Meredith Deliso, Nadine El-Bawab, Jaclyn Lee, Alex Stone, Jenna Harrison and Connor Burton contributed to this report.