GARDEN GROVE (CNS) - Evacuation centers in Orange County were filling up Sunday as firefighters and engineers continued looking for ways to prevent a major disaster at a plant in Garden Grove, where a tank filled with a flammable and toxic chemical has been overheating since Thursday.

Some 50,000 people have been evacuated from parts of Garden Grove and neighboring communities. The evacuation zone was north of Trask Avenue, south of Ball Road, east of Valley View Street and west of Dale Street, and includes the entire city of Stanton, along with parts of Garden Grove, Anaheim, Westminster and Cypress.

A new evacuation center was opened at the Golden West College Gymnasium in Huntington Beach, and centers were also operating at the Garden Grove Sports and Recreation Center and the Cypress Recreation and Community Center. An evacuation center that accepts pets was opened at Los Amigos High School in Fountain Valley, but many pets were being housed outside other evacuation centers, which were not allowing them inside.

Four evacuation centers that opened earlier were already full: Freedom Hall in Fountain Valley, Kennedy High School in La Palma, Ocean View High School in Huntington Beach and Savannah High School in Anaheim.

Additionally, all Orange County 24 Hour Fitness clubs and several locations in the southwest Los Angeles area have been opened to offer restrooms and showers, phone-charging and air-conditioned space to rest for impacted residents.

Multiple schools in the Garden Grove, Magnolia, Savanna, Westminster and Cypress school districts were closed until further notice.

The tank was still intact Sunday, one day after firefighters reported that an overnight foray into the facility revealed temperatures there were rising by about 1 degree per hour and not decreasing as hoped, the Orange County Fire Authority noted.

In a more hopeful update Sunday morning, the agency said a specialized team of subject matter experts made another venture into the critical area late Saturday and found a potential crack in the tank.

"During that operation, our firefighters went in and were able to visualize the tank. What they found was a potential crack in the tank, which could potentially be relieving some of the pressure in there," said TJ McGovern, interim fire chief for the OCFA.

He added that authorities were vetting the new information, which could "change our trajectory and our strategy for this event."

"Last night was a successful operation," McGovern said. " ... We're not there yet, but this was a step in the right direction."

On Saturday, Unified Incident Commander Craig Covey said workers were able to see a gauge that's covered by water, and it revealed the temperature had increased to 90 degrees from 77 degrees Friday morning. The team was currently allowing the tank to "cure at a slower rate and reducing its (building) overpressure," Covey said.

Additionally, the OCFA is "bringing people in from all over the country, talking to people all over the place, trying to come up with additional options. Letting this thing just fail and blow up is unacceptable to us."

He added that "very aggressive" contingency plans are being employed in case the tank blows up or leaks, including fire and medical emergency plans, though the only people currently at risk were the firefighters and police officers on scene.

Authorities are trying to establish "some diking and damming and divert it to a spot that could be a holding area" to prevent the fluid from "getting into our storm drains, our river channels and ultimately into the ocean, (causing) an environmental disaster," Covey said.

Air quality monitors said they had not detected any contaminants in the atmosphere near the facility thus far.

Authorities responded to GKN Aerospace Transparency at 12122 Western Ave. at about 3 p.m. Thursday after the tank began venting vapors and triggering a sprinkler system designed to spray water on it to cool the material inside, methyl methacrylate used to manufacture acrylic plastics.

Evacuation orders were issued, but later lifted Thursday night when crews believed they were making progress mitigating the situation. But Friday morning, the orders were re-instituted "due to changing conditions," OCFA officials said. As the morning wore on, the situation worsened, and the evacuation zone was expanded to create a roughly one-mile buffer area around the tank.

Officials clarified Saturday that the evacuation area was divided into a handful of zones, including three circular "blast zones" closest to the plant, with likely severe, moderate and light damage in the event of an explosion.

Beyond that, three other zones were identified: Areas of flammability where fire or flash fire could occur, areas that were "immediately dangerous to life and health, where it would cause injury if anybody inhales or is impacted by the product in question," according to Nick Freeman, division chief with the OCFA, and a large "non-hazardous zone" where people could still smell odors from a leak.

Covey said a spill of the chemical is actually the "best case scenario, believe it or not," favorable to an explosion and possible plume of toxic material spreading over the area.

He stressed that "there is no active gas leak, no plume in the area," but warned residents to heed the evacuation warnings and remain out of the area due to the possible spill or explosion. Officials said air quality was being actively monitored and all readings were still within healthy limits.

It was unclear what caused the material in the tank to overheat.

GKN Aerospace, a global supplier of vehicle and aircraft components that manufactures acrylic plastics, posted the following statement on its website Saturday:

"There is a serious and evolving situation regarding a thermal issue in a chemical storage tank at our Garden Grove site in California. The situation remains ongoing and we are fully focused on working with emergency services, specialized hazardous material teams and the relevant authorities to ensure the safety of the local community, our employees and everyone else involved. We sincerely apologize for the significant disruption to the many local residents and businesses who have had to be evacuated. We are working tirelessly with all relevant experts to resolve this situation as safely as possible and in a timely manner and are deeply grateful for the continued skill and dedication of the Orange County emergency services."

In 2021, GKN Aerospace paid about $900,000 to settle multiple environmental violations, including failing to keep emission records and operating equipment without a permit, according to the OC Register, which cited the South Coast Air Quality Management District.

California Gov. Gavin Newsom proclaimed a state of emergency Saturday. The proclamation directs the California Governor's Office of Emergency Services and all state government agencies to support Orange County and impacted local jurisdictions to address the emergency. It also unlocks additional emergency response resources and authorities, including making state- owned properties and fairgrounds available to provide shelter for evacuated residents as necessary.

California Attorney General Rob Bonta on Saturday cautioned anyone who would jack up prices on needed items during a state of emergency.

"California's price gouging law protects people impacted by an emergency from illegal price gouging on housing, gas, food and other essential supplies," he said. "If you see price gouging, I encourage you to immediately file a complaint with my office online at oag.ca.gov/report or contact your local police department or sheriff's office."

The Orange County District Attorney's Office announced Saturday afternoon that it has established an anonymous tipline and online reporting form to gather information regarding the incident.

"Anyone with information related to the circumstances leading up to this incident, including but not limited to specific details of the release, information about the industrial operations of the facility, the quality and frequency of maintenance of the tanks and systems at issue, and any other relevant information at GKN Aerospace Transparency Systems, is encouraged to call the Orange County District Attorney Anonymous Tip Hotline at 714-347-8714 or fill out an anonymous online form at www.ocdistrictattorney.gov," the office stated.

A Garden Grove emergency hotline was operated at 714-741-5444, and an Orange County public information hotline was available at 714-628-7085.