Kentucky tornadoes: up to 100 feared dead in historic US storms

Rescuers worked into the night searching for survivors after what could be the longest tornado in US history left a trail of destruction from Arkansas to Kentucky, part of a vast stormfront that is believed to have killed up to 100 people.

Kentucky governor Andy Beshear said the path of devastation was about 227 miles (365km) long, which, if confirmed, would surpass the 218-mile Tri-State tornado in 1925, which killed at least 695 people and destroyed 15,000 homes across Missouri, Illinois and Indiana.

Elsewhere, the death toll from multiple tornadoes included six people in Illinois, where an Amazon depot was hit; four in Tennessee; two in Arkansas, where a nursing home was destroyed; and two in Missouri.

Burgess said it could take a day and potentially longer to remove all the rubble. Creason added the rescue efforts had been complicated by tornado damage to the main fire station and emergency services hub.

He also released details of a relief fund to help those affected.

In Illinois, six people were killed in the collapse of the Amazon warehouse in Edwardsville, with another injured worker airlifted to a hospital, fire chief James Whiteford said.

Investigators searched the rubble throughout the day for additional victims. Whiteford said 45 people had survived, but authorities were uncertain Saturday evening whether anyone was still unaccounted for, as workers were in the midst of a shift change when the centre was struck by the tornado about 8.30pm Friday.

The Retail, Wholesale and Department Store Union, which has been trying to organise workers at an Amazon facility in Alabama, criticised the company for keeping the Illinois site open during a weather emergency.