CHICAGO—Search efforts at an Amazon facility in Illinois where at least six people were killed in a tornado were expected to take several days, but authorities said they did not expect to find additional survivors. The company has not said how many people were in the building not far from St. Louis when the tornado hit at 8:35 p.m. Friday—part of a swarm of twisters across the Midwest and the South that leveled entire communities. Authorities said they didn’t have a full count of employees because it was during a shift change and there were several part-time employees. Both sides of the warehouse used to prepare orders for delivery collapsed inward and the roof caved, according to Edwardsville Fire Chief James Whiteford. Authorities received reports of workers being trapped and the fire unit arrived within six minutes, Whiteford said. Police helped pull people from the rubble. While 45 employees survived, …