Michael Schumacher and Rubens Barrichello enjoyed a third consecutive one-two finish - but it was far from straightforward for the Ferraris in an incident-packed United States Grand Prix.

Just eight cars finished the 73-lap race at the Indianapolis Motor Speedway, with Williams BMW driver Ralf Schumacher taken to hospital after a horror smash.

The first incident came within seconds of the start and accounted for four cars; the Jaguar of Christian Klien, the Jordan of Giorgio Pantano, Gianmaria Bruni in the Minardi and the Sauber of Felipe Massa.

Barrichello made a clean getaway from pole but behind him a melee ensued, with the Toyota of Cristiano da Matta seemingly the instigator as he slammed on his brakes heading into turn one.

Klien took evasive action but only succeeded in being hit by Pantano, with Bruni and Massa also involved as they trundled onto the grass and out of the race.

It led to the safety car being deployed for the first time as the cars of Klien and Pantano were embedded into one another in the middle of the circuit at that particular corner.

It took the trackside marshals five minutes to remove all the debris, resulting in the safety car staying out for four laps, but once again there appeared to be a moment of controversy.

Michael Schumacher expertly managed to get a tow behind Barrichello coming out of the final turn, however, he appeared to marginally pass his team-mate as they crossed the start-finish line, which is not allowed under race rules.

But timings later confirmed Schumacher was behind Barrichello by less than a thousandth of a second, his overtaking manoeuvre effectively millimetre-perfect.

Fernando Alonso had been running third behind the red machines when the right-rear tyre blew on his Renault towards the end of the long pit straight, with the car travelling at a speed of around 200mph.

The nose of the car turned violently into the wall, with Alonso sliding along the track for at least 100 yards under braking before ploughing into a polystyrene advertising block in the run off area where he eventually came to rest unscathed.

The safety car had been threatened, but was stood down, only to be deployed again one lap later for the most frightening of all the incidents, involving Ralf Schumacher.

The Williams of the German was merely seen coming out of the final turn backwards before slamming into the trackside wall at a speed again of around 200mph.

Schumacher came to rest in the middle of the pit straight, with pieces of his battered car strewn across the track, and for a few moments it appeared as if he was in trouble as he sat motionless in his car.

Other cars flew past the 28-year-old, with the skills of the evasive drivers ensuring there was no further carnage, before the safety car took to the track again.

It took 11 minutes for Schumacher to be removed from his car and placed in an ambulance which took him to the nearby Methodist Hospital, used for drivers involved in accidents at the circuit, just five minutes away.

As the ambulance drove slowly down the straight, thousands of fans in the main grandstand rose to applaud Schumacher.

An official statement from BMW Williams later revealed Schumacher had not suffered any injury, with a spokesman confirming: "Ralf was taken to a local hospital as a precaution.

"He is conscious, can move everything and is in a stable condition. The team are not yet aware of what caused the incident."

The safety car remained out for nine laps prior to the end of which da Matta retired due to gearbox failure, and there then followed a string of other retirements.

The BAR of Jenson Button, Nick Heidfeld in the Jordan, the Jaguar of Mark Webber and Giancarlo Fisichella's Sauber all suffered problems, while Juan Pablo Montoya was black-flagged by the race stewards.

The Colombian was seen sprinting from the grid to the pits to collect the spare BMW Williams just as the field was ready to pull away for the formation lap.

The stewards deemed Montoya had joined the race in the spare car in circumstances where he had not left the grid within 15 seconds of the start, a seemingly harsh penalty, but the rules were strictly enforced.

By the end of the race, Schumacher had clinched his eighth win from nine races this season, and the 78th of his career, beating Barrichello by 2.9 seconds and extending his lead in the championship to 18 points over the Brazilian.

They were followed home by Takuma Sato in his BAR, the Renault of Jarno Trulli and the Toyota of Olivier Panis, with the McLarens of Kimi Raikkonen and David Coulthard sixth and seventh.

Hungarian Zsolt Baumgartner brought his Minardi home in eighth for his first world championship point, and the team's first since Australia 2002.

It was a sombre but relieved Michael Schumacher in the media conference after the race as he had been made aware his younger brother was unhurt.

``That was my biggest concern, and the worst thing was seeing Ralf in the car for so long,'' said Schumacher.

``They were telling me [over the radio] that he was okay, but I have heard these kind of things before in the past and it has not been the case.

``But I later learned that everything was all right and at the end of this race that's all that matters.''