Valtteri Bottas and Max Verstappen both crashed and seriously damaged their cars during the second practice ahead of the Austrian Grand Prix as the high-altitude track in the Alps showed its perilous side on Friday.

Mercedes and Red Bull blamed gusty winds in the montane surroundings for the incidents, which caused the 90-minute session to be red-flagged twice.

A third big-name driver narrowly avoided a similar crash as Sebastian Vettel also spun off the track but his Ferrari came to a standstill just before the barriers, limiting damage to his tires only.

Before his crash, Bottas posted the second fastest time of the session, trailing Ferrari driver Charles Leclerc by 0.331 seconds.

Championship leader Lewis Hamilton, who led the first session in his Mercedes, had the fourth best time, 0.443 behind Leclerc.

Bottas slammed his Mercedes into the barriers after he lost control of the rear and spun off the track at Turn 6, leaving the front of his car heavily damaged.

The mishap came less than 15 minutes after Verstappen slid off the track backward in Turn 10, badly damaging the right rear of his Red Bull.

"Hard to say what happened, maybe it was the wind," Verstappen said. "It's still only Friday so we have time to repair everything for tomorrow."

Bottas and Verstappen are the last two winners of the race, in 2017 and 2018, respectively. Neither was hurt in the crashes.

Mercedes team principal Toto Wolff said Bottas couldn't be blamed.

"Suddenly you have three, four kph more and you are beyond the limit," Wolff said about the strong wind affecting the drivers.

Red Bull motorsport adviser Helmut Marko added that Verstappen "wasn't driving faster as before in that turn but the gust just swept away the rear."