Emergency officials have lifted an evacuation order for some of the tens of thousands of people who live near a damaged tank containing a hazardous chemical in Southern California. Authorities said Monday that they are reducing the evacuation zone and it is safe for some residents of Garden Grove to go home. Officials ordered about 50,000 residents to evacuate their homes in Garden Grove, near Los Angeles, on Thursday after a tank containing methyl methacrylate overheated, causing pressure to build up inside. Officials said earlier Monday that a crack that was discovered in the tank a day earlier caused the internal temperature to drop, eliminating the risk of a catastrophic explosion.