A potentially catastrophic chemical emergency in Southern California may be shifting away from fears of a massive explosion and toward what federal officials now believe is a more likely a low-volume leak situation, according to the Environmental Protection Agency.  

The crisis centers on an overheating chemical storage tank at a GKN Aerospace facility in Garden Grove, about 35 miles southeast of Los Angeles. The tank contains thousands of gallons of methyl methacrylate, a highly flammable industrial chemical used in plastics and aerospace manufacturing. 

EPA Administrator Lee Zeldin said Sunday that officials now believe a leak is more likely than an explosion. 

More than 40,000 residents across parts of Orange County have been evacuated since authorities warned the tank could rupture or explode. California Gov. Gavin Newsom declared a state of emergency as crews worked around the clock to cool the tank and prevent a disaster.