May 25, 2026, 4:13 PM EDT What sent a chemical storage tank in Garden Grove, California, to the verge of either leaking or blowing up? And how did authorities avoid the worst-case scenario — a massive vapor explosion that threatened to destroy buildings and expose residents to toxic plumes? Over the last several days, Southern California officials — with help from state and federal agencies — have tried to avert what they feared could be one of the worst chemical incidents in California history.