GARDEN GROVE, Calif. (AP) — A crack that formed by chance in an overheated chemical tank in Southern California relieved pressure and helped avert a catastrophic explosion, but officials said Tuesday it still wasn't safe enough for 16,000 people living closest to the aerospace plant to return home.

The crisis forced 50,000 people to evacuate in and around the Orange County city of Garden Grove last week. Most returned home after the crack formed over the Memorial Day weekend, but the risk of a smaller explosion or potential spill kept evacuation orders in place for about a third of residents.

Isabel Mendez was among those still waiting to return to her mobile home. She said she broke out in a rash on her face and developed tingling lips and a sore throat while evacuating last week. After spending several expensive nights in a hotel, she is now staying with her mother north of Los Angeles.

She remains uncertain about returning home because she does not trust official assurances that the area is safe.

"Of course it is still dangerous," she said.