An ammonia gas leak from a tanker truck in a hotel parking lot in Oklahoma hospitalized dozens of people and prompted a shelter-in-place order. The incident happened Wednesday night at the Holiday Inn Express parking lot in Weatherford, about 70 miles outside Oklahoma City. Hundreds of residents were forced to evacuate. Officials lifted a shelter-in-place order Thursday morning, hours after firefighters wearing gas masks went door to door in Weatherford, waking people up and telling them to leave because of the anhydrous ammonia leak. An oil field worker staying at the hotel where the truck had been parked said he heard a “faint pop” Wednesday night and noticed a smell minutes later. He and a coworker left their room and hustled into a hallway and then an elevator filling up with a pungent odor. Once outside, they saw their vehicles underneath a cloud of ammonia, said Michael Johnson, of Nacogdoches, Texas. “The smell itself punched me,” he said. He took off running, but noticed his roommate wasn’t with him and saw that he had run for their trucks. He said a police officer managed to save his coworker. “His lips were purple and frozen shut,” Johnson said. “His eyes were bloodshot red. His skin was all red.” Johnson found one person stumbling and gave him a shirt to put over his mouth. At one point, he looked at the smoke and saw they were surrounded, thinking “We’re going to die.” In total, the incident hospitalized 45 people. Five were airlifted to Oklahoma City-area hospitals. Police said several people remain in intensive care and most are in stable condition. Dozens more were treated at three “casualty collection points,” police said. Approximately 14 officers were exposed to anhydrous ammonia, with five sustaining chemical burns to their airways, police said. Many first responders were treated at the scene, police said. No fatalities have been reported, police said Thursday evening. Video of the incident showed an ammonia plume blanketing the parking lot on Wednesday night. The driver of the tanker truck involved is believed to have parked in the lot to get a room at the hotel, according to Weatherford Police Chief Angelo Orefice. The leak is believed to be accidental and is under investigation, police said. A possible mechanical failure on a valve or a faulty seal are being considered as potential causes, according to Orefice.