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 Tuesday 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.

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.

Vonn’s father, Alan Kildow, spoke with her by phone and said that she’s “mad at the way things turned out.” She told him that she landed in a clump of sugar snow, or ice crystals, that caused her fall forward, he said.

“She’s a tough character,” Kildow said in a phone interview. “She will be back.”

But she could be looking at 6 to 8 months before she’s back on skis.

Comebacks are nothing new for Vonn, who has also been afflicted by injuries at her last six major championships.

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.

On Tuesday, 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 31/2 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 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 said.

Said Atle Skaardal, the women’s race director: “I can confirm that the visibility was great, there were no problems, and the course was also in good shape.”