Bearman's Haas hit the barriers with a force of 50G at Spoon corner after approaching Franco Colapinto's Alpine with a significant speed differential between the cars, the US-owned team said.
As the Haas swerved left to avoid contact, the car went onto the grass and through a marker board as the 20-year-old lost control at 308kph with the safety car then deployed in a key moment of the race.
Haas said Bearman, who was seen limping after getting out of the car, escaped without broken bones but had a right knee contusion from the impact.
"He had huge closing speed against the car in front, so had to take avoiding action and went on the grass and crashed. Scary," team boss Ayao Komatsu told Sky Sports TV during the race.
Such speed differences on track have been highlighted as a consequence of the sport's new engine era and regulations and drivers' need to manage an increased electrical element.
Spaniard Sainz, a director of the Grand Prix Drivers' Association, said drivers had feared just such an accident and called on the International Automobile Federation (FIA) to act.
"We've been warning them about this happening, this kind of closing speeds and this kind of accidents were always going to happen," he said. "I'm not very happy with what we've had up until now.
"Hopefully we come up with a better solution that doesn't create these massive closing speeds and (produces) a safer way of going racing.
"Here we were lucky there was an escape road. Now imagine going to Baku or going to Singapore or going to Vegas (street circuits) and having this kind of closing speeds and crashes next to the walls."
Mercedes boss Toto Wolff agreed the sport had to look into it.
"The regulations are at a very immature way and actually the FIA and us teams we're going to analyse the accident very carefully to see how we can avoid these things," said the Austrian.