Michael Schumacher, the retired seven-time Formula One champion who often braved death on the tracks, is fighting for his life after an off-piste skiing accident in the French Alps.

The German racing legend, who turns 45 at the end of the week, was helicoptered off a mountain in the upmarket Meribel resort on Sunday after falling and hitting his head on a rock while skiing off-piste with his 14-year-old son.

News of the accident stunned the Formula One community and racing stars joined German Chancellor Angela Merkel and legions of fans in wishing him a speedy recovery.

Initially described as non-life-threatening, his condition gradually deteriorated and the hospital where he was being treated eventually announced late on Sunday that Schumacher was critical, had serious brain trauma and had undergone an emergency operation.

In an update to reporters on Monday, doctors at the hospital in the southeastern city of Grenoble said that while it was too early to make a prognosis on the famous patient, he was fighting for his life.

“He is in critical condition, his condition can be described as life threatening,” Jean-Francois Payen, head of the intensive care unit, told reporters.

Stephan Chabardes, the professor who operated on Schumacher, said the former racer arrived in hospital on Sunday in an agitated state – his arms and legs jerking uncontrollably – and was not able to answer questions.

His condition “rapidly deteriorated” and he fell into a coma, he told reporters.

Payen said he was immediately operated on and still suffered from “serious and diffuse brain lesions”, which indicates his injuries are not localised but more widespread.

He added that Schumacher would not be alive if he had not been wearing a helmet.

“Given the violence of the impact, his helmet partially protected him. If someone had had this type of accident without a helmet, they would definitely not be here,” he said.

In a statement released later on Monday, Schumacher’s wife Corinna and the rest of his family thanked well-wishers and gave a special nod to the doctors treating him.

“We would like to thank the medical team who, we know, do everything possible to help Michael,” Corinna said in a statement.