As a number of cars approached a 90-degree turn next to a grandstand, video shows Floersch's auto suddenly rocketing across the inside of the turn and briefly impacting another car-driven by Japanese driver Sho Tsuboi-while flying through air.
Dramatic footage of the accident was captured on the race broadcast, and has since gone viral around the globe.
After sitting in 16th place, Floersch reportedly hit the back of Jehan Daruvala on the straight before losing control. Speed-trap data from the braking zone of that corner shows Floersch had been travelling at 276.2 km/h.
The cause of the crash has yet to be officially investigated, but it is believed to have happened after Floersch bumped into the back of a vehicle driven by Indian racer Jehan Daruvala when he slowed down for yellow warning flags.
"It was such a scary moment", he told Autosport.com.
"She hit Jehan's right-rear and that spun her around straight into Lisboa, and she flew into the other auto". Frits van Amersfoort, the owner of her team - Van Amersfoort Racing - said she must have had an "angel on her shoulder".More news: Former 49ers RB Jarryd Hayne Charged With Sexual Assault
The Macau Grand Prix Organising Committee said: "All were conscious during transit to the hospital and are now receiving medical treatment".
In addition to Floersch, fellow driver Sho Tsuboi, a race marshal and two photographers were also transported to hospital.
Sophia Floersch suffered a spine fracture after the crash at the Macau Grand Prix.
The teenager later tweeted to say she was OK and and confirmed she will have surgery on Monday.
Running 16th, she lost control in a contact down the straight, launched off a kerb and bounced off Tsuboi's TOM's Racing vehicle.More news: Rain Is Forecasted for Fire-Ravaged California This Week
Media reports said Tsuboi has lumbar pain. Both were under observation in a local hospital.
Floersch had reassured her fans on Twitter Sunday evening, before going into surgery the following day.
"Thanks to the FIA, HWA AG Official and Mercedes AMG who are taking great care of me".
Van Amersfoort Racing said on Twitter: "Today was a very hard day for our team at the #MacauGP".
It's probably the worst crash you've ever seen. She previously competed in Formula 4 and the Ginetta Junior Championship.
The race was immediately red-flagged and did not restart until an hour after the incident.More news: CNN says White House preparing to eject reporter Jim Acosta again
The race, which was won eventually by 19-year-old Dan Ticktum of London, was delayed for over one hour to fix the barrier and tend to the injured parties. It was eventually won by Dan Ticktum.