What made Texas blast so devastating?
19 April 2013 Last updated at 11:00 BST
Emergency services are still searching for survivors after a blast at a US fertiliser plant that police say killed up to 15 people.
More than 160 people were injured and dozens of buildings destroyed in the Texan town of West, near Waco after a blast at a fertiliser plant.
Emergency services officials said ammonia may have caused the explosion, but why was the blast so devastating?
Frank Mair, a chemist from the University of Manchester, spoke to BBC Breakfast.