AT least 21 people have been treated for burns after an event in California where they tried to walk on hot coals.

The San Jose Mercury News reported that at least three people were taken to hospital, with most suffering second- or third-degree burns, after the event for a US motivational speaker.

Tony Robbins was hosting a four-day Unleash the Power Within gathering at the San Jose Convention Centre. Attendees said a crowd went to a park where 12 lanes of hot coals were set up on the grass. Witness Jonathan Correll said he heard "screams of agony".

■united states