Two women's snowboardcross riders were taken off the course on stretchers after accidents during women's Olympic qualifying on Sunday.

Jackie Hernandez of the U.S. was nearing the end of the 1,200-meter course when she was knocked unconscious after slamming her head into the snow at Rosa Khutor Extreme Park. Hernandez, 21, briefly sat up after several minutes and was communicating with medics before being transported down the mountain.

Hernandez sustained a concussion while racing in Austria in December but was released following a series of exams.

The crash came minutes after Helene Olafsen of Norway was also taken off the course with an injury. The other 22 riders during the first heat were able to navigate the course unscathed.

"It's always a big bummer when you see some of your friends go down and get injured and you never really know because you're kind of just sitting there," said Lindsey Jacobellis of the U.S. "I try to zone out and focus on what I've got to do."

The accidents came a day after Russian skicross racer Maria Komissarova of Russia sustained a spinal injury during training on the same slope.