Vonn, four-times overall World Cup champion and the finest woman skier of her generation, fell to the ground grimacing as she slowed down after the finishing line and she staggered away with what appeared to be either a hip or back injury.
Vonn, who finished 24th, spent just under an hour in the medical treatment tent before being escorted to a waiting car and driven away. The 33-year-old walked the few metres to the car with great difficulty.
An ambulance was called but was not needed.
With two months to go before the Pyeongchang Winter Olympics, Vonn said on Twitter that she had "an acute facet (spinal joint) dysfunction" but said she might still compete in Sunday's race which is another Super G.
"I got compressed on the sixth gate and my back seized up. Rested and had a lot of therapy tonight. We will see how I feel tomorrow and then decide if I will race," she said.
The U.S. team said Vonn "skied through pain but didn’t have power to push."
Vonn, downhill gold medallist in Vancouver in 2010, missed the 2014 games in Sochi because of a knee injury.
Gut, recently recovered from a serious knee injury, lost her balance high on the course, fell and flew into the safety netting. She was able to walk away after being disentangled by course officials.
Gut, the overall World Cup winner in 2016 and bronze medallist in the downhill at the Sochi Olympics, tore an anterior cruciate ligament in her knee at the same venue at the world championships in February.
The race, on a shortened course, was held in difficult conditions and was interrupted several times as wind blew clouds of snow across the course.
Switzerland's Jasmine Flury, who had never previously finished on the podium in a World Cup race, was a surprise winner, starting from 14th, in one minute 2.59 seconds.
She finished 0.10 seconds ahead of compatriot Michelle Gisin while Liechtenstein's Tina Weirather was third.
Flury admitted she had enjoyed the best of the very changeable conditions.
"I don't know what to say, unbelievable," she said. "Everything went well - no wind, good vision, sun," she said.
(Editing by Ed Osmond)
