As Max Verstappen pipped pole sitter Carlos Sainz to the first corner there was "carnage" behind with marshalls rushing to Zhou trapped in his stricken car.
George Russell's Mercedes, Alpine's Esteban Ocon, Yuki Tsunoda (Alpha Tauri) and the Williams of Alex Albon were also involved.
Zhou's car was catapulted upside down, the Chinese rookie's head saved by his car's roll hoop-halo as it skidded off across a gravel trap and over tyre barriers into the catch fencing, where it bounced back to finish semi-upright in a stationary position.
Detailed replays of the accident were not available immediately until Zhou had been rescued from his car.
He was attended by emergency evacuation medical crews and lifted out, transferred on to a stretcher and taken by ambulance to the circuit medical centre.
Albon was also taken to the medical centre before being transferred to Coventry Hospital by helicopter for further precautionary tracks.
The sport's ruling body the International Motoring Federation (FIA) advised that both drivers were conscious and were being checked over and evaluated.
They later announced that Zhou was "in good health and has left the medical centre".
The normal speed for Formula One cars in that part of the circuit is around 240 kph.
In re-runs of the start, it appeared that Russell, starting eighth, moved to his right after a poor start and collided with Zhou's Alfa Romeo as the pair strove to stay ahead of Pierre Gasly.
This triggered Zhou's wild excursion off-circuit and dragged other cars into further less serious multiple collisions around them.
In a separate additional announcement, the FIA confirmed also that several protestors had tried to run on to the circuit following the red flag.
"We also confirm that after the red flag, several people attempted to enter the track," said the statement. "These people were immediately removed and the matter is now being dealt with by the local authorities."
The field filed back to the pits after the collision as a specialist extraction crew attended Zhou, who remained in his car, until he was lifted clear.
Other drivers including Russell climbed from their cars to assist Zhou following the collision.
The teams involved were all in frantic action repairing their damaged cars after the incident in preparation for a re-start.
In a radio statement, Alfa Romeo said: "Zhou is conscious, he is talking, there are no fractures. Considering the circumstances, he is pretty good, pretty well."
This was not the first collision in which the 'halo' device was instrumental in saving a driver from serious injury — Roy Nissany survived after another car driven by Dennis Hauger landed on top his cockpit in which he was saved by the halo. Both escaped unhurt.
After a near one hour delay the race restarted in the original starting order, with the grid reduced to 17 with the retirements of Zhou, Albon and Russell.
Unlike the original start Sainz managed to held off Verstappen to the first corner as the Spaniard seeks his first ever F1 win in his 150th start after securing his maiden pole.
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