(Reuters) - The Emilia Romagna Grand Prix at Imola was halted after 33 of 63 laps on Sunday following a collision between the Mercedes of Valtteri Bottas and Williams of George Russell.
Both drivers climbed out of their wrecked cars but the amount of debris scattered across the track in the high-speed accident triggered the safety car and then brought out red flags.
Russell, who has a long-term Mercedes contract, had been trying to overtake the Finn for ninth place. Replays of the incident were inconclusive.
Red Bull's Max Verstappen was leading the race with seven- times world champion Lewis Hamilton, who had started from pole position, down in ninth after making a rare error on the damp track and sliding off across the gravel.
The Briton, who had been second before the incident, had to pit for a new front wing.
The cars returned to the pits to await a re-start.
(Reporting by Alan Baldwin, editing by Ed Osmond)