A tornado that ripped through Moore, a suburb of Oklahoma City, Oklahoma, on Monday afternoon left at least 24 dead, including nine children, and a trail of destruction that some survivors compared to a “war zone”.

With winds at over 320 km/hr, the tornado — classified by the National Weather Service as the second most-powerful EF-4 type on the enhanced Fujita scale — flattened houses, blew off rooftops and tore through several schools.

U.S. President Barack Obama declared a major disaster in the area and said on Tuesday morning, “Neighbourhoods were destroyed. Dozens of people lost their lives. Many more were injured. And among the victims were young children, trying to take shelter in the safest place they knew — their school.” He said he had been in touch with Oklahoma Governor Mary Fallin, Moore Mayor Glenn Lewis and promised the Federal Emergency Management Agency would provide whatever assistance was required for “the hard work of recovery and rebuilding that lies ahead.”

Mayor Mr. Lewis said to NBC news, “The whole city looks like a debris field... It looks like we have lost our hospital. I drove by there a while ago and it’s pretty much destroyed.

More than 200 emergency responders were working in Moore all night. The community of 56,000 people was said to be bracing for another “long, harrowing day” on Tuesday after State medical examiners said the death toll was likely to rise further. More than 240 were said to have been injured. Worst hit were two elementary schools, Briarwood and Plaza Towers. At Plaza Towers, evacuation was reportedly not complete when the tornado struck. Oklahoma, situated in what is called “Tornado Alley”, has faced similar twisters before, particularly in May 1999 when wind speeds of 480 km/hour damaged 600 homes and about 100 businesses.

While two or three schools were also hit in 1999, children were out of school at the time so fatalities were limited. This week’s destruction was the deadliest U.S. tornado since 161 people were killed in Joplin, Missouri, two years ago.