More than 300 students and staff were forced to evacuate a London school after an e-cigarette exploded.

Fire crews believe the electronic cigarette was being charged through a USB port with the wrong adaptor.

A spokesperson for London Fire Brigade said: “It’s extremely important the correct type of charger is used with e-cigarettes and other electrical products to prevent fires from starting, and never leave items like e-cigs on charge overnight while you’re sleeping.”