Officials in Southern California say a possible crack in a 7,000-gallon toxic chemical tank at a GKN Aerospace facility may be relieving internal pressure and reducing the risk of a catastrophic vapor explosion.

The tank contains methyl methacrylate, a hazardous chemical, and concerns initially triggered evacuation orders for about 50,000 residents across Orange County.

Fire officials said they are still confirming whether the crack eliminates the threat of a “BLEVE” explosion, though other explosion and leak risks remain.

Air monitoring has not yet detected a toxic release, but nearby communities remain under evacuation as crews continue cooling and stabilizing the tank, NBC News has reported.

Authorities warn the situation could still escalate, with officials calling it potentially one of the worst chemical incidents in California history.