At least six Amazon.com Inc workers were killed at a warehouse near St. Louis on Friday night when a series of tornadoes roared through the area, ripping off the roof and reducing a wall longer than a football field to rubble.
Several workers remained unaccounted for as rescuers searched for anyone who might still be trapped at the Edwardsville, Illinois facility, authorities said.
Fire chief James Whiteford said 45 people had made it out safely as of Saturday afternoon. He said six people were confirmed killed so far, and he expected recovery efforts to last for at least three more days.
Colleagues and family members desperate for news about loved ones gathered outside the 500,000 square foot mess of concrete and steel.
Amazon truck driver Emily Epperson, 23, said she was anxiously waiting for information on the whereabouts of her workmate Austin McEwan late Saturday afternoon to relay to his girlfriend and parents.
"We're so worried because we believe that, you know, he would have been found by now," she told Reuters.
One mother told a St Louis Fox news station that her son Clayton Cope, a 29-year-old maintenance worker, was dead.
Police were yet to officially release names. A press briefing was expected about 5pm. central time.
Earlier, Fillback said about 50 workers were believed to be at the warehouse when it was hit by an extreme "weather-related event" about 8:30 p.m. Friday. A devastating swarm of tornadoes ripped through six US states, leaving a trail of death and destruction at homes and businesses that stretched more than 200 miles.
At least 30 workers were transported by bus from the scene and others may have left on their own, Fillback said. He said it had been difficult to get an exact number of workers who might be unaccounted for because the warehouse did not have "a set staff."
"You have concrete, and you have things hanging. It's quite windy outside, so things are unstable, so they have to shore those things up so that they can be safe," Fillback said. "Our first responders will continue to work this scene until everyone is accounted for."
Drone footage from the scene showed rescue workers picking through a huge area of debris in the pre-dawn darkness.
Amazon CEO Andy Jassy posted on Twitter that the company was "heartbroken over the loss" of its staff members and would continue to work closely with the local authorities on the rescue efforts.
"It gives me shivers," Kathie Burnett, 67, said. She was a delivery driver at Amazon until two weeks ago when she quit because of health reasons.
"I would have been standing right in the middle of that track," she said pointing to what remained of the facility. "There would have been 100 trucks in there last night and you didn't see one this morning, did you?"
