RENO, Nev. - The death toll rose to nine Saturday in an air race crash in Reno as investigators determined that several spectators were killed on impact as the 1940s-model plane appeared to lose a piece of its tail before slamming like a missile into a crowded tarmac.

Moments earlier, thousands had arched their necks skyward and watched the planes speed by just a few hundred feet off the ground before some noticed a strange gurgling engine noise from above. Seconds later, the P-51 Mustang dubbed the Galloping Ghost pitched oddly upward, twirled and took an immediate nosedive into a section of white VIP box seats.

The plane, flown by a 74-year-old veteran racer and Hollywood stunt pilot, disintegrated in a ball of dust, debris and bodies as screams of "Oh my God!" spread through the crowd.

National Transportation Safety Board officials were on the scene Saturday to determine what caused Jimmy Leeward to lose control of the plane, and they were looking at amateur video clips that appeared to show a small piece of the aircraft falling to the ground before the crash. Witnesses who looked at photos of the part said it appeared to be an "elevator trim tab," which helps pilots keep control of the aircraft.

Reno police also provided a GPS mapping system to help investigators recreate the crash scene.

"Pictures and video appear to show a piece of the plane was coming off," NTSB spokesman Mark Rosekind said at a news conference. "A component has been recovered. We have not identified the component or if it even came from the airplane ... We are going to focus on that."

Investigators said they also recovered part of the tail section, where the tab is located.

A tour near the site offered to journalists Saturday evening revealed debris spread in a fan-shape over more than an acre around a crater roughly 3 feet deep and as much as 8 feet across. Based on the crater's location, it appears the P-51 Mustang went straight down in the first few rows of VIP box seats, or about 65 feet in front of the leading edge of the grandstand.

Yellow crime tape surrounded the scene and spectator seats remained askew.

Among the dead were the pilot and eight spectators. Officials said 69 people were treated at hospitals, including 36 who have been released and 31 who remain there. Nine were in critical condition late Saturday.

Doctors who treated the injured said it was among the most severe situations they had ever seen because of the large number of people, including at least two children younger than 18 who are not among those in critical condition.

Injuries included major head injuries, facial trauma and limb injuries, including amputations, said Dr. Myron Gomes, chief trauma surgeon at Renown Regional Medical Center.

"I've seen more patients, but never this many patients with this number of severe injuries," added Dr. Michael Morkin, chief of Renown's emergency department, who trained at Cook County General Hospital In Chicago.

"It was traumatic," he said.

Despite the large number of dead and injured, witnesses and people familiar with the race say the toll could have been much worse had the plane gone down in the larger crowd area of the stands. The plane crashed in a section of box seats that was located in front of the grandstand area where most people sat.

"This one could have been much worse if the plane had hit a few rows higher up," said Don Berliner, president of the Society of Air Racing Historians and a former Reno Air Races official. "We could be talking hundreds of deaths."

Some credit the pilot with preventing the crash from being far more deadly by avoiding the grandstand section with a last-minute climb, although it's impossible at this point to know his thinking as he was confronted with the disaster and had just seconds to respond.

Witnesses described a horrible scene after the plane struck the crowd and sent up a brown cloud of dust billowing in the wind. When it cleared moments later, motionless bodies lay strewn across the ground, some clumped together, while others stumbled around bloodied and shocked.

"I saw the spinner, the wings, the canopy just coming right at us. It hit directly in front of us, probably 50 to 75 feet," said Ryan Harris, of Round Mountain, Nev. "The next thing I saw was a wall of debris going up in the air. That's what I got splashed with. In the wall of debris I noticed there were pieces of flesh."

Ambulances rushed to the scene, and officials said fans did an amazing job in tending to the injured. Just that morning, the 25 emergency workers at the air show had done a drill for such a large-scale emergency like this.

"We run through what we do in the event of an incident," said Ken Romero, director of the Regional Emergency Medical Service Authority. "We walked through how to respond, where the multi-casualty incident bus is and what is on the bus (by way of equipment), how to set up the treatment zones and how to triage."

The crash marked the first time spectators had been killed since the races began 47 years ago in Reno. Twenty pilots including Leeward have died in that time, race officials said.

It is the only air race of its kind in the United States. Planes at the yearly event fly wingtip-to-wingtip as low as 50 feet off the ground at speeds sometimes surpassing 500 mph. Pilots follow an oval path around pylons, with distances and speeds depending on the class of aircraft.

The disaster prompted renewed calls for race organizers to consider ending the event because of the dangers. Officials said they would look at everything as they work to understand what happened.

Another crash, on Saturday, came at an airshow in Martinsburg, W. Va., when post-World War II plane, a T-28, crashed and burst into flames. The pilot was killed.

In Reno, the Mustang that disintegrated into the crowd had minor crashes almost exactly 40 years ago after its engine failed. According to two websites that track P-51s that are still flying, it made a belly landing away from the Reno airport. The NTSB report on the Sept. 18, 1970, incident says the engine failed during an air race and it crash landed short of the runway.

P-51 historian Dick Phillips of Burnsville, Minn., said Saturday the plane had had several new engines since then as well as a new canopy and other modifications.

Leeward, the owner of the Leeward Air Ranch Racing Team, was a well-known racing pilot. His website says he has flown more than 120 races and served as a stunt pilot for numerous movies, including "Amelia" and "The Tuskegee Airmen."

In an interview with the Ocala (Fla.) Star-Banner last year, he described how he has flown 250 types of planes and has a particular fondness for the P-51, which came into WWII relatively late and was used as a long-range bomber escort over Europe. Among the famous pilots of the hot new fighter was double ace Chuck Yeager.

The National Championship Air Races draw thousands of people to Reno every September to watch various military and civilian planes race. Local schools often hold field trips there, and a local sports book took wagers on the outcomes.

The FAA and air race organizers spend months preparing for air races as they develop a plan involving pilot qualification, training and testing along with a layout for the course. The FAA inspects pilots' practice runs and briefs pilots on the route maneuvers and emergency procedures.

John Townes, a Reno pilot, said the plane didn't sound right moments before the crash.

"It wasn't quite vertical. It was at a very slight angle and because of that I think it probably saved a lot of people," he said. "Normally when you see an air crash, you see recognizable wreckage. There was nothing, just little bits of metal."