A man set himself on fire in a part of Washington DC close to the US Capitol, local officials have said.
A fire official said a man has been flown to the hospital after suffering major burns.
Witnesses said they saw the man dump a red canister of petrol on his head and then set himself on fire.
One witness Vanessa Sink, wrote on Twitter: “Just witnessed the craziest thing ever… a man set himself on fire and danced down the Mall.
“A runner and passerby put the flames out. I didn’t see him light the match, but I saw the flames engulf his body. It was incredible.”
She said the man was picked up by a helicopter and transported to a medical facility.
The incident happened just after 4.20pm EST (9.20pm BST) on Friday in a part of Washington DC called the National Mall, between Capitol Hill and the White House.
It comes at a period of heightened tensions in the capital, a day after a woman was shot for trying to ram her way into the White House and Capitol grounds and weeks after 12 people were shot at a city navy yard.
DC police spokeswoman Saray Leon said: “We have a report of a man on fire at 7th and Independence.”
She said the man was “conscious and breathing” when firefighters responded.
It is believed a police officer with the city’s Metro Police attempted to help put out the blaze.
Fire Department spokesman Tim Wilson said the man has life-threatening injuries.
His name and age were not immediately known.
A dog was seen checking the seen with a police handler afterwards.