At least nine people were killed Saturday when a powerful tornado hit the central Plains state of Kansas and levelled the town of Greensburg, a state civil defence official confirmed, according to DPA. Seventeen of the 63 injured were in critical condition. Authorities declared a state of emergency, imposed a ban on driving and ordered the town evacuated. A thorough search of rubble in the town was launched to seek possible further victims. "Everything disappeared," Greensburg resident told local broadcaster KSN. "Nothing remains." Greensburg's 1,500 residents are to be housed in emergency shelters. Electricity has been cut to the entire town. The tornado hit Greensburg at 9:45 pm Friday. The whirlwind wreaked havoc along a 1,000-metre stretch of the town. Tornado chaser Darin Brunn described the killer tornado as "massive and slow moving." According to the American Red Cross, around 90 per cent of houses in Greensburg have been destroyed or badly damaged. Local television station KWCH showed footage of survivors in the darkness and climbing out of houses that had been reduced to rubble. A tornado warning was reportedly sounded 20 minutes before the tornado struck. Houses then literally exploded around the occupants, as the extreme low pressure inside the storm coupled with powerful, circular winds to wreak destruction. The tornado overturned cars, ripped petrol pumps out of a filling station and snapped trees like twigs. Around 30 patients had to be rescued from the rubble of the local hospital.