MAYFIELD  -   US emergency workers searched Sunday for survivors of ferocious tornadoes that killed dozens of people across several states and left towns in ruins, as the governor of hard-hit Kentucky warned that cadaver dogs were still finding bodies. President Joe Biden called the rare late-season burst of twisters in the US heartland “one of the largest” storm outbreaks in American history, and on Monday night declared a major federal disaster in Kentucky. He had previously issued an emergency declaration for the hard-hit state, but upgraded it at the governor’s request to allow for additional aid. Both federal and local officials have cautioned the death toll, for now at 94, could still rise. While the heads of the Homeland Security Department and the Federal Emergency Management Agency (FEMA) went to Kentucky to assess the situation, stunned residents began sifting through the rubble of their homes and businesses.