SCHLADMING, Austria » All it took was a moment. Lindsey Vonn landed hard and tumbled face first with a piercing shriek.

Just like that, her season was done. The star American skier was on the ground with two ligaments in her right knee torn, a bone in her lower leg broken.

The cascading fall down the slope during the super-G at the world championships today knocked out the four-time World Cup champion for the rest of the season, the latest and most serious in a string of injuries for Vonn at skiing’s biggest events.

The U.S. team said in a statement it expects her back for the next World Cup season and the 2014 Sochi Olympics, which start a year from this week.

The harrowing accident came after Vonn was lifted into the air off a jump in the opening race at the championships. As she hit the ground, her right leg gave way and she spun down face first, throwing an arm out to protect herself. She ended up on her back as she smashed through a gate.

On the television feed, Vonn was clearly heard screaming an expletive as she landed, then a despairing "Yes, yes," when someone asked, "Are you hurt?"

Race leader and eventual champion Tina Maze watched with her mouth agape. The concern also was obvious on the face of Vonn’s sister, Laura Kildow, who has been traveling with her full time this season.

For 12 minutes, Vonn lay on the snow getting medical treatment before being airlifted by helicopter to a hospital in Schladming.

Vonn tore her anterior cruciate ligament and medial collateral ligament in her right knee, U.S. ski team medical director Kyle Wilkens said in a statement. The broken bone was described as a "lateral tibial plateau fracture."

Christian Kaulfersch, the assistant medical director at the worlds, said Vonn left the Schladming hospital this afternoon and will have surgery in another hospital.

"She first wanted to go back to the team hotel to mentally deal with all what has happened," Kaulfersch said.

Team physician William Sterett, who was with Vonn, declined to offer any more information when contacted by The Associated Press.

Comebacks are nothing new for Vonn, who has also been afflicted by injuries at her last six major championships — from a thumb she sliced on a champagne bottle at the 2009 worlds in Val d’Isere, France, to a bruised shin that she cured with Austrian cheese at the Vancouver Olympics.

This one, however, could prove the biggest test yet for the 28-year-old who won the downhill at the 2010 Vancouver Olympics.

Vonn took a month off this season after being hospitalized for an intestinal illness in November, and had just regained her form with two wins last month.

That was evident at the start of her today’s run. She led Maze by 0.04 seconds at the first checkpoint and was just 0.12 back at the second interval and seemingly on her way to a medal, if not victory.

What went wrong is a matter of debate.

The start of the race was delayed by 3½ hours because of fog hanging over the course and it began in waning light at 2:30 p.m local time. Even before Vonn’s crash, a course worker fell and also had to be airlifted. He was reported to have broken his nose.

All the delays made for what skiers call flat light — overcast and dreary conditions — when Vonn raced.

"Lindsey did a great job on top and Lindsey has won a lot of races in flat light so the flat light was definitely not a problem," U.S. Alpine director Patrick Riml told the AP.

"We are upset obviously with what happened but if you don’t know the facts and why they decided to start and what the weather forecast was it’s hard to say without any reasoning," Riml said. "And they probably had a reason, otherwise they wouldn’t have started."

It was difficult to say exactly when Vonn lost control.

"She jumped a little bit in the wrong direction and started to correct that a little bit in the air and put a lot of pressure on the outside ski exactly in the landing and she couldn’t hold the pressure and then (she crashed)," said Atle Skaardal, women’s race director for the International Ski Federation.

Skaardal defended the decision to race.

"I can confirm that the visibility was great, there were no problems, and the course was also in good shape," he said. "I don’t see that any outside factors played a role in this accident. … The other factors were like they were supposed to be for ski racing."

Vonn’s list of injuries at major championships is long.

Two years ago, she pulled out midway through the last worlds in Garmisch-Partenkirchen, Germany, because of a mild concussion. At the 2010 Vancouver Olympics, Vonn skied despite a severely bruised shin to win the downhill and take bronze in the super-G.

At the 2009 worlds in Val d’Isere, she sliced her thumb on a champagne bottle after sweeping gold in the downhill and super-G, forcing her out of the giant slalom. At the 2007 worlds in Are, Sweden, Vonn injured her knee in training and missed her final two events.

And at the 2006 Turin Olympics, she had a horrific crash in downhill training and went directly from her hospital room to the mountain to compete in four of her five events.

The conditions today varied from racer to racer, and as the light began to fade even more, organizers stopped the race after only 36 of the 59 skiers had come down.

Maze skied immediately before Vonn.

"I saw it was a very high jump, so I knew I had to take the right line to make the next gate," she said. "World championship races often have special conditions and the mistakes from the girls were not because of the slope."

The two competitors who started immediately after Vonn, former overall winner Maria Hoefl-Riesch of Germany and local favorite Anna Fenninger of Austria, each skied off course. In all, six racers who started the course failed to finish. Still, Skaardal said he never thought about stopping the race.

"It’s not a very difficult course but in some parts you couldn’t see anything," said Fabienne Suter of Switzerland, who finished fifth.

Vonn’s teammate Julia Mancuso also thrived in the difficult conditions and won the bronze medal.

"It’s the same for everybody," U.S. speed coach Chip White said. "Everyone had to wait for a long time and that’s always difficult. And the holds were every 15 minutes so it really doesn’t give you a chance to go and do something else. You’re always kind of on edge at the ready. It’s a difficult situation but everybody had the same difficult situation."

Olympic giant slalom champion Viktoria Rebensburg of Germany had to ski through a bank of fog at the beginning of her run.

"There was a lot of fog but it’s something we’re used to," Rebensburg said, adding that the race was fair. "If you look at the results the top super-G skiers are in front so I think it was OK."

However, Rebensburg allowed that the course was "not really perfect" because of inconsistent snow conditions.

Not long after Vonn was injured, NBC hosted a news conference in New York to discuss its coverage of the Sochi Games. A poster of a smiling Vonn hung in the room next to one of snowboarder Shaun White, evidence of the network’s unsurprising expectations that she would be one of the biggest stars in Sochi.

The network’s executives chose to put a positive spin on the injury.

"We expect her to be the comeback Olympian of the year," NBC Sports Group Chairman Mark Lazarus said.

Associated Press writer Eric Willemsen in Schladming and AP Sports Writer Rachel Cohen in New York contributed to this report.