At least nine people have died and 56 more were injured when a vintage aircraft crashed into the ground at an air show in the US state of Nevada, a spokesman and video images showed.
Mike Houghton, president and CEO of Reno Air Races, told a news conference hours after the crash that mechanical problems might have caused a World War II-era fighter plane to plunge into the grandstands at a Nevada air show on Friday.
Stephanie Kruse, a spokeswoman for the Regional Emergency Medical Service Authority, said that of the 56 people injured, 15 people were critically injured and another 13 were seriously hurt in the crash. The remaining 28 had non-life-threatening and non-serious injuries, she said.
She said that a number of the injured had been transported by private vehicles, and that they had not been included in the initial casualty count.
"This is a very large incident, probably one of the largest this community has seen in decades,'' Kruse told the Associated Press. "The community is pulling together to try to deal with the scope of it. The hospitals have certainly geared up and staffed up to deal with it.''
Kate Grey, a spokesperson for the St Mary's health centre in Reno, told Al Jazeera that hospitals had sounded an "all-clear" signal at about 9:05pm local time (04:05GMT on Saturday).
A West Virginia Air National Guard spokesman has said a World War II-era plane has also crashed at an air show.
Lt Nathan Mueller said the T-28 aircraft crashed on Saturday at a Martinsburg airfield, but he did not have any details on the pilot's condition.
Officials said they did not immediately know of any injured spectators.
'Like a bomb went off'
Killed in the Nevada crash was the pilot, 74-year-old movie stunt pilot Jimmy Leeward, and at least two others.
"It's just like a massacre. It's like a bomb went off," said eyewitness Gerald Lent, quoted by the Reno Gazette-Journal. "There are people lying all over the runway."
Kate Grey, spokesperson for St Mary's regional medical centre in Reno, speaks to Al Jazeera.
The aircraft was a World War II P-51 Mustang fighter plane, called the Galloping Ghost, capable of speeds in excess of 800km/hr.
Mike Draper, a spokesman for the event, said the plane was a lap or two into the race when its pilot called in a mayday.
"We don't know why it crashed. The pilot did call in. He did pull out of the lap, which is what they do. They usually pull up, directly up to clear the race track," he added.
The plane spiraled out of control and then appeared to disintegrate on impacting with a box-seat area in front of a grandstand.
Houghton confirmed that the rest of the scheduled races had been cancelled, and that the National Transportation Safety Board (NTSB) was investigating the crash.
Maureen Higgins, a spectator at the event who has been attending air races for 16 years, said the pilot was on his third lap when he lost control of the aircraft. She was sitting about 30 metres away from the point of impact, and said she watched in horror as the man in front of her began to bleed after debris hit him in the head.
"I saw body parts and gore like you wouldn't believe it. I'm talking an arm, a leg," Higgins said "The alive people were missing body parts. I am not kidding you. It was gore. Unbelievable gore."
The National Championship Air Races draws thousands of people to Reno every September, with spectators given a chance to watch various military and civilian planes race. The races have attracted increased scrutiny in recent years over safety concerned, particularly after four pilots were killed in 2007 and 2008.