All evacuation orders tied to a failing chemical tank in Southern California that sparked fears of a catastrophic explosion have been lifted, local authorities announced Tuesday evening.The Orange County Fire Authority said in a social media post that officials have determined there is no threat of an explosion, fire or chemical leak and no risk to the public.On Monday, officials announced the evacuation zone was shrinking after the "worst-case scenario" of a catastrophic explosion had been averted. But about 16,000 people remained under evacuation orders.Earlier Tuesday, officials said the temperature inside the tank was holding steady at 92 degrees with only the use of onsite sprinklers to cool it. Once the methyl methacrylate -- the chemical in the tank -- cools and turns into a solid, the threat of a release goes away, Orange County Fire Department Capt. Wayhowe Huang said at a press conference Tuesday.No chemical has leaked out, and there is nothing in the air, Huang said.Water is sprayed on a damaged tank at GKN Aerospace in Garden Grove, Calif., May 25, 2026.KABC"The most catastrophic and worst-case scenario was mitigated and resolved," Orange County Fire Authority (OCFA) Interim Chief TJ McGovern said during a Monday press briefing, when the evacuation orders were first pared back.The tank is located at an aerospace facility in Garden Grove, about 30 miles south of Los Angeles. During the height of the crisis, when officials thought they faced only two options -- an explosion or chemical spill -- about 50,000 people in the city of Garden Grove and several surrounding communities were under evacuation orders.The situation began unfolding 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.Water is sprayed on a damaged tank at GKN Aerospace in Garden Grove, Calif., May 25, 2026.KABCThe "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 caused 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 said a crack in the tank, discovered by firefighters 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.A family sets up tents after evacuating from their homes after a chemical leak from a large storage tank threatened residents, in Garden Grove, California, May 24, 2026.Blake Fagan/AFP via Getty ImagesIn a statement on Monday, GKN noted that its technical specialists worked with OCFA "to assess the storage tank more closely" on Sunday evening.Popular Reads"The team safely and successfully removed external insulation material from the tank in order to help advance efforts to cool its contents," the company said.Orange County District Attorney Todd Spitzer, the top prosecutor in Garden Grove, has launched a criminal probe into the ongoing chemical tank incident at GKN Aerospace, ordering the company not to destroy or manipulate any records, his office said.The probe seeks to determine how a major military and commercial aircraft gear manufacturer could have allowed such a toxic failure to occur, according to the district attorney."This is an incredibly volatile situation with extraordinary efforts being made by first responders to prevent a potentially catastrophic disaster," Spitzer said in a statement on Monday.Spitzer has also established an anonymous tip line and online reporting form, calling on anyone with information to come forward -- including current and former employees of the company who might offer insight into the quality control and safety at the site."Given the very real risk to human life as a result of this event, it is crucial that anyone who has information about this incident or the industrial operations of GKN Aerospace Transparency Systems, Inc. come forward and report it so that it can be thoroughly investigated by law enforcement," he said.GKN declined to comment specifically on the district attorney's investigation, but pointed to its Monday statement."We are continuing to work around the clock with the OCFA, the EPA and all relevant federal, state and local agencies to mitigate the ongoing risk of a leak. We remain extremely thankful for their dedication and hard work," the company said."We apologize for the ongoing disruption this incident is causing and our priority remains its safe resolution, so that residents can return to their homes as quickly as possible."ABC News' Meredith Deliso, Nadine El-Bawab, Jaclyn Lee, Alex Stone, Jenna Harrison, Connor Burton and Sasha Pezenik contributed to this report.