The French Stéphane Peterhansel, 57 years old and holder of the record for victories in the event (14 car and motorcycle titles), was the victim of an accident at km 212 at the wheel of his hybrid Audi.
His co-pilot, Édouard Boulanger, suffered a back injury and was evacuated by helicopter to a local hospital, organizers said.
This marks the end of the adventure for the Audi team, which was second overall, 22 minutes behind al-Attiyah.
At the wheel of his Toyota, the outgoing champion set the best time of the 358 km special of a stage between Hail and Riyadh (918 km in total), shortened by 100 km due to the torrential rains that fell on Saudi Arabia this week.
He was 3 min 29 sec ahead of Frenchman Sébastien Loeb (Prodrive) and 8 min 52 sec of South African Henk Lategan (Toyota) who beat French driver Guerlain Chicherit (Prodrive) to the post.
Sébastien Loeb 6th with almost two hours behind
This 6th stage was synonymous with a nightmare for his three pursuers.
In addition to Peterhansel, the Spaniard Carlos Sainz (Audi hybrid) "
was injured
" at this same Km 212, according to the organizers.
"
The crew is unscathed and is waiting to be able to repair their vehicle before trying to resume their race
", they specified shortly after the accident of the fourth in the general classification.
And the Saudi Yazeed Al Rajhi, third at the wheel of his Toyota, suffered a mechanical problem at the 216th km.
In the provisional general classification, Henk Lategan takes second place with 1 h 06 min behind the Qatari.
Brazilian Lucas Moraes (Overdrive) is third (1 h 13 min).
Sébastien Loeb, who had won the 4th stage after a difficult start to the competition, found himself sixth with nearly two hours of cumulative delay.