The Canadian Formula One Grand Prix was halted after 25 of the scheduled 70 laps by torrential rain on Sunday.
Red Bull's world champion and pole sitter Sebastian Vettel was leading when the race was red flagged and cars ordered to park on the starting grid as rain lashed the across the Circuit Gilles Villeneuve.
The race was the first run in wet weather this season, making the twisting and challenging layout all the more treacherous.
"It's just way too dangerous, (FIA race director) Charlie (Whiting) has done the right thing to stop the race," said Red Bull team boss Christian Horner. "In conditions like these, drivers are just absolute passengers.
"The water picks the car up, they've got no drive and an accident is so easy to have, especially with the walls so close".
The wet conditions resulted in the first safety car start of the season, with the car staying out for the first four laps.
The conditions, with heavy spray and standing water, made for a tough afternoon for drivers with cars skidding and spinning out around the circuit.
"It's undriveable, undriveable," Vettel said over the team radio.
Lewis Hamilton's bid for a Canadian hat-trick, after winning twice before in Montreal, had already ended after just eight laps when he collided with McLaren team mate Jenson Button.