A vintage World War Two fighter plane crashed near the grandstand at a Nevada air race on Friday, killing at least three people, including the elderly pilot, and injuring more than 50 others, officials said.
At least 15 people were in critical condition after the crash at the Reno Air Races, which a spokesman for the event called a "mass casualty situation" in a written statement.
The plane, a P-51 Mustang dubbed the "Galloping Ghost" that was being flown by well-known pilot Jimmy Leeward (74), crashed into a box seat area in front of the main grandstand at about 4.20pm, said Mike Draper of the public relations firm R&R Partners, which represents the race.
Renown regional medical centre spokeswoman Kathy Carter confirmed that two other people had been killed.
A federal aviation administration official said separately that multiple fatalities and critical injuries were reported.
Authorities are investigating the cause, but one of the event’s organisers said there were indications that mechanical problems were to blame.
Video apparently taken from the stands and posted on YouTube showed a plane plunging nose-down into the tarmac as spectators were heard gasping: "Oh, my God."
Debris billowed near the crash site, and officials then told attendees to remain where they were so emergency workers could get to the scene.
The head of the Reno Air Racing Association, Michael Houghton, put the number of injured at 54 people and confirmed the pilot was killed.
Mark Hasara of Cedar Rapids, Iowa, is a veteran of the Air Force who attended the race and witnessed the crash. "As soon as I saw his nose pointed at the ground, I knew he wasn't going to recover," Mr Hasara said.
The Reno crash is the latest in a spate of fatal air show accidents since August.
Last month, the pilot of an aerobatic airplane died in a fiery crash in front of shocked onlookers at a weekend air show in Kansas City. In Michigan last month a wingwalker at an air show near Detroit plunged about 200 feet to his death as he tried to climb onto a helicopter in midair.
The Reno Air Races, which began in the mid-1960s, feature planes facing off in multi-lap races at an airfield north of Reno.
Reuters