Oklahoma storm chaser: I felt like crying today
21 May 2013 Last updated at 09:00 BST
In Oklahoma city a whole suburb appears to have been flattened by what has been described as one of the most powerful tornadoes ever to hit the United States.
It tore through the town of Moore killing at least 24 people, including seven children, as it ripped up buildings, schools, cars and anything in its path.
Ben Holcomb, who describes himself as a storm chaser, explained that he was following the tornado as it entered Moore City and told Today presenter Sarah Montague what he saw.
"Once I get a chance to think about it, it's not going to sit very well with me," he said.
"I've felt like crying quite a few times today," he added.
First broadcast on BBC Radio 4's Today programme on Tuesday 21 May 2013.