Formula One’s governing body said it had opened an investigation into Romain Grosjean’s Bahrain Grand Prix crash on Thursday as the French driver hailed those who helped him escape the fireball.

Grosjean suffered burns to his hands after his Haas car split in two, penetrating a metal barrier and erupting in flames, in Sunday’s race.

The Frenchman left hospital on Wednesday and in an Instagram post accompanying video footage pointed to “the moment I realised I was going to live”.

He highlighted the ‘professionalism’ of the marshal with the extinguisher and FIA doctor Ian Roberts. “I told him he was a hero, he went into the fire as much as he could to save me,” he said of Roberts.

“I felt Ian’s hands pulling me over the barrier and knew I was safe. I remember every second of it and life will never be the same again, but I’m sure for the best,” added the driver. “I met with death and that is the worst feeling I ever had. But I’m alive and will enjoy every second of life and every small win in a much better way from now on.”

The International Automobile Federation (FIA) expected its investigation to take six to eight weeks. It will look at all safety devices and the role of track marshals and medical intervention team.