The Orange County chemical leak crisis eased Monday, but officials warned the emergency is not over.
Fire officials in Garden Grove, California, said the worst threat from an overheating chemical tank at a GKN Aerospace facility has been eliminated. But they also said crews must keep working around the clock to prevent a fire, spill, or other hazard.
The tank contains methyl methacrylate, a volatile and highly flammable liquid used in making plastics and aerospace materials. California Gov. Gavin Newsom declared a state of emergency after the chemical incident forced mass evacuations in Orange County. The state proclamation said the tank held about 5,000 to 7,000 gallons of methyl methacrylate at the GKN Aerospace site in Garden Grove.
Officials said Monday that the risk of a massive blast, known as a boiling liquid expanding vapor explosion, was no longer the main concern. Still, they kept a smaller evacuation zone in place because the tank and chemical material remain unstable.
Fire Crews Used Millions of Gallons of Water
Orange County Fire Authority officials said firefighters used a deluge sprinkler system to keep the tank cool. Division Chief Craig Covey said crews also used a ground monitor flowing about 1,250 gallons of water per minute.
“We’re talking millions and millions of gallons,” Covey said during a Monday update, according to CBS Los Angeles.
The goal was simple. Crews needed to keep the chemical tank from overheating and building dangerous pressure. Officials said the tank temperature had been about 100 degrees Saturday night, then dropped and leveled near 93 degrees by Monday evening.
Under normal conditions, officials said the tank would stay around 50 degrees with its cooling system working. That system was not working, so hazmat teams kept watching the temperature trend and consulting chemical experts.
Evacuation Zone Reduced, but 16,000 Still Affected
Garden Grove officials reduced the evacuation zone Monday by about 65 percent. That allowed many residents to return home after days of uncertainty.
The new evacuation zone still covers homes and businesses for about 16,000 residents. The City of Garden Grove emergency page lists the active zone as south of Orangewood Avenue, west of Dale Street, east of Knott Street, and north of Garden Grove Boulevard. Residents can check official updates through the City of Garden Grove emergency page.
Authorities urged people outside the reduced zone not to assume the crisis had fully ended. Officials said the area remains active because crews still face hazards inside the incident site.
Sen. Adam Schiff also warned residents not to ignore evacuation orders. He said nothing is worth risking lives by going back into a restricted area too soon.
Officials Say Returned Residents Can Feel Safe
Orange County Health Care Agency official Dr. Regina Chinsio Kwong said people allowed to return home Monday could feel safe. She said officials had not found contamination that would require residents to clean the outside of their homes.
Covey said runoff water from the firefighting operation was being tested as part of normal hazardous materials response. He said teams also placed downstream barriers to capture any floating material.
Officials said water monitoring had remained clean during the operation. They also said there was no need for residents outside the active evacuation area to wash down homes, outdoor furniture, or walkways.
The Environmental Protection Agency says methyl methacrylate can irritate the eyes, skin, nose, and throat during exposure. The agency also notes that workplace and environmental monitoring can help manage risk during industrial incidents. More chemical information is available through the EPA methyl methacrylate fact sheet.
Seven Arrested Inside the Evacuation Area
Garden Grove Police Chief Amir El Farra said seven people had been arrested since the emergency began. One person was arrested on suspicion of looting, and six others were arrested on suspicion of prowling.
“Unfortunately, during incidents like this, we do have bad actors,” El Farra said.
Police said officers would keep high visibility patrols and plain clothes details in the affected neighborhoods. El Farra said evacuees returning home should expect to see more officers in the area.
Authorities said the Orange County District Attorney’s Office would prosecute criminal cases connected to the evacuation zone.
State and Federal Help Followed Mass Evacuations
The emergency began May 21, 2026, when responders arrived at the GKN Aerospace facility on Western Avenue in Garden Grove. California’s emergency proclamation said the incident involved a chemical storage tank that began heating up and releasing toxic fumes.
Newsom issued the state emergency proclamation on May 23, 2026. The order directed state agencies to support local response efforts and told residents to follow emergency officials’ instructions. The full proclamation is posted by the California Governor’s Office.
The City of Garden Grove said President Trump also issued a federal emergency declaration to support local response. That declaration allows federal help during the incident and recovery period.
Major outlets including The Associated Press and Reuters reported that officials no longer considered a catastrophic explosion the main threat, while smaller risks remained.
Why Officials Say the Crisis Is Not Over
The biggest fear has eased, but the incident still carries risk. Officials said crews must keep cooling the tank, watching temperatures, testing runoff, and monitoring the site for chemical hazards.
The reduced evacuation zone shows progress. It also shows officials still do not view the area as fully safe.
For thousands of residents, the emergency has already disrupted homes, work, school, and daily life. Many people can now return, but about 16,000 remain affected by evacuation orders.
Orange County officials said they will consider more reentry when conditions improve. Until then, their message remains firm. The blast threat may be off the table, but the Garden Grove chemical crisis is not over.