Days after mass evacuations were ordered in Orange County, the next few hours could be crucial in dealing with a volatile chemical tank at a Garden Grove aerospace company that has threatened to either explode or cause a major spill.

What to Know A compromised chemical storage tank at Garden Grove’s GKN Aerospace facility is threatening to leak its toxic contents or explode in what authorities called an unprecedented emergency. The hazardous materials situation began Thursday night when firefighters responded to reports of a problem with the tank containing a flammable liquid called methyl methacrylate.

Days after mass evacuations were ordered in Orange County, the next few hours could be crucial in dealing with a volatile chemical tank at a Garden Grove aerospace company that has threatened to either explode or cause a major spill.

Tens of thousands remain evacuated as emergency crews try to secure a tank loaded with 7,000 gallons of methyl methacrylate at an aerospace plastics facility in Orange County.