Shiffrin led after the first run, but was under heavy pressure in the second after a cannon run by Hector.
In the middle of the second run, Shiffrin lost her balance and crashed into the safety net.
It was a tough crash and American leaders and medical personnel rushed to her aid.
Shiffrin couldn't get up on her own and left the slope in a stretcher.
As she approached the finish area, the home crowd cheered and Shiffrin, 29, waved.
Has cleared her knees
No official update on the American's injury has been given.
I just heard that her knees have cleared, so that's positive. But we'll see what it is, in the best case, it's not long-term, says Sara Hector to TT over the phone.
Hector was 32 hundredths behind Shiffrin after the first run and made a cannon run in the second.
She loved the situation and flashed a big smile before the start.
I enjoyed the moment, says Hector, who hasn't been satisfied with the season start.
This season didn't start super strongly mentally, now I've worked really well the last few weeks and step by step, the skiing has started to work again. There were some technical small details that didn't fit, says she.
Celebrating in the jacuzzi
The 32-year-old Swedish Olympic gold medalist from Beijing 2022 was ultimately superior.
Second-place Zrinka Ljutic, Croatia, was 54 hundredths behind, and third-place Camille Rast, Switzerland, over a second behind.
On Sunday, there's a slalom in Killington, so no bigger celebration is waiting after her sixth World Cup victory.
Today, I'll enjoy myself and do what I feel like doing this afternoon. It's about celebrating. I might sit in the jacuzzi at the hotel for a while, says Sara Hector contentedly.
In March 2023, Mikaela Shiffrin took her 87th World Cup victory and thus surpassed Ingemar Stenmark, whose record of 86 wins had stood for 34 years.
Now, the world's most successful alpine skier had the chance to reach new, fantastic levels with her 100th career victory.
But Shiffrin has had a tough time in Killington, and this time it ended in horror in the American ski resort.
