Marussia driver Jules Bianchi has been taken to hospital after a crash at the Japanese Grand Prix.
The Frenchman lost control at the same spot at which recovery vehicles were attending the Sauber of Adrian Sutil, who had crashed on the previous lap.
The FIA said Bianchi was unconscious as he was taken from the Suzuka track.
In wet conditions, the 25-year-old's incident, which led to the race being called off, happened shortly after the rain intensified.
Mercedes driver Nico Rosberg, who finished second to team-mate Lewis Hamilton, said: "My thoughts are with my colleague. They have given us some information and it seems very, very serious."
Hamilton said he had heard Bianchi was "severely injured".
Sutil said: "It was the same as happened to me a lap before.
"I had aquaplaning in Turn Eight. The rain was increasing and the tyres were going down, the light was going down. It was hard to see.
"I was following Jules very close and had a spin and hit the wall. I was OK and then one lap later, under waved yellows, Jules was in the same trouble.
"I have no more information but we are all aware of the situation that he is not in the paddock and we hope he is OK."
Asked whether Bianchi's car had hit the recovery crane, Sutil said: "No comment on that."
Bianchi, a member of Ferrari's young driver programme, is in his second season in F1.
He scored a memorable ninth place in Monaco this year, giving the back-of-the grid Marussia team their first points since their debut in 2010.
(BBC)