A tanker truck spewing hazardous gas in an Oklahoma hotel parking lot forced hotel guests and hundreds of residents to evacuate in the overnight hours. Authorities say three dozen people were treated after being overcome by fumes. Some were flown to hospitals in Oklahoma City. The anhydrous ammonia leak happened late Wednesday in Weatherford. Schools closed, and several nursing homes evacuated. A shelter-in-place order was lifted Thursday morning. The city's police chief said the leak happened after the truck driver had parked behind a Holiday Inn Express for the night. Officials said the leak might be due to a mechanical failure. Cleanup efforts could take several days.