Rescue crews on Sunday searched through rubble for survivors a day after tornadoes tore across the United States, killing at least 22 people and shattering homes and businesses, officials said. US President George W. Bush called it a "sad day" for devastated communities in the states of Missouri, Oklahoma and Georgia and promised emergency federal aid. Missouri's department of emergency management said 14 people were confirmed dead in the state, with scores more injured. "We are still conducting some search and rescue today," department spokeswoman Susie Stonner told AFP, adding that some of the injured were "in hospital in critical condition."