Nine people have been killed and at least 50 injured after a World War II fighter plane crashed at an air show in the US state of Nevada.
The vintage aircraft spiralled out of control and plunged into a VIP area at the Reno Air Races.
The elderly pilot of the P-51 Mustang was among the dead.
Video taken from the stands and posted on YouTube showed a plane crashing nose-down during a race against several other aircraft.
The air show is hugely popular, drawing thousands of spectators annually.
After the crash, on the third lap of the race, witnesses could be heard gasping: "Oh, my God."
A huge brown cloud rose up moments afterwards and debris was strewn at high velocity over a wide area.
It is believed the plane had climbed to an altitude of 400ft before plunging at a steep angle into the ground.
Michael Houghton, chief executive of the Reno Air Racing Association, told a news conference the crash was "considered a mass casualty situation".
Stephanie Kruse, a spokeswoman for the Regional Emergency Medical Service Authority, said emergency crews took a total of 56 injury victims to three hospitals.
She said they also observed a number of people being transported by private vehicle, which they are not including in their count.
Deputy police chief Dave Evans said the remains of seven victims were recovered from the tarmac at the site, adding to two people who had already been confirmed dead by a local hospital.
Mike Draper, a spokesman for the race organisers, said the plane was piloted by 74-year-old Jimmy Leeward.
He is a well-known local veteran airman and a movie stunt pilot who was flying a P-51 Mustang called The Galloping Ghost.
On Thursday, he talked about team tactics for the weekend races, saying: "Right now, I think we've calculated out, we're as fast as anybody in the field, or maybe even a little faster, but to start with, we really didn't want to show our hand, until about Saturday or Sunday.
"We've been playing poker since last Monday, and so it's ready - we're ready to show a couple more cards, so we'll see Friday what happens, and Saturday we'll probably go ahead and play our third ace, and on Sunday, we'll do our fourth ace."
In a June video posted at the website for the air race, Leeward said The Galloping Ghost raced from 1946 to 1950 in the Cleveland Air Races.
He said his crew cut 10ft off the plane's length and made other modifications to improve its aerodynamic abilities and reach speeds of 500mph.
Authorities were investigating the cause, but an official at the event said there were indications that mechanical problems were to blame.