Michael Schumacher still in critical condition

                                       Schumacher and his wife Corrina

PARIS -- Seven-time Formula One champion Michael Schumacher was in critical condition after undergoing brain surgery following a weekend skiing accident that has stunned drivers, fans and athletes around the world.

The Grenoble University Hospital Center said the retired racing driver arrived at the clinic in a coma on Sunday and underwent immediate surgery for a serious head trauma.

It was not clear whether the 44-year-old Schumacher was still in a coma but the hospital statement, which was signed by a neurosurgeon, an anesthesiologist and Marc Penaud, the hospital's deputy director, said "he remains in a critical condition."

Schumacher fell while skiing off-piste in Meribel in the French Alps on Sunday morning and hit his head on a rock, according to a statement from the resort. Resort managers said he had been wearing a helmet and was conscious when rescuers first responded to the scene.

The Meribel resort initially said Schumacher had been taken to Grenoble for tests and authorities said his life was not in danger.

But the situation began to appear more serious when the resort said that orthopedic and trauma surgeon Gerard Saillant had traveled from Paris to the hospital in Grenoble to examine Schumacher. German news agency dpa said it was Saillant who operated on Schumacher when he broke his leg during a crash at the Silverstone race course in 1999.

In an email to The Associated Press, Schumacher's manager, Sabine Kehm, said the champion German driver was on a private skiing trip and "fell on his head."

"We ask for understanding that we cannot give running updates on his condition. He wore a helmet and was not alone," Kehm said. Schumacher's 14-year-old son, Mick, was skiing with his father when the accident happened, the resort said.

ESPN F1 reported that Schumacher's wife and children were at the hospital, along with Jean Todt, his former Ferrari team boss and now president of motorsport's governing body, the FIA. Ross Brawn, who worked with Schumacher at Ferrari and Mercedes F1 teams, was reportedly also at the hospital, where a gathering of media and fans was swelling.

As news of the accident spread, Formula One drivers used social media to wish Schumacher a quick recovery.

His former Ferrari teammate, Felipe Massa, who himself recovered from life-threatening head injuries sustained at the Hungarian Grand Prix in 2009, wrote on Instagram, "I am praying for you my brother!! I hope you have a quick recovery!! God bless you Michael."

British former world champion Jenson Button said posted that his "thoughts are with Michael Schumacher at this tough time. ... Michael more than anyone has the strength to pull through this."

Romain Grosjean of Lotus tweeted: "All our thoughts to Schumi and his family! Hope you will recover soon #legend #Schumi."

Support also came from leading German sports personalities, ranging from the NBA to soccer. Dallas Mavericks power forward Dirk Nowitzki said his thoughts were with Schumacher, while Lukas Podolski, who plays for Arsenal in the English Premier League, tweeted: "Bad news from Switzerland: please get well soon, Michael Schumacher. All the best for you, my friend! #getwellsoon #MichaelSchumacher."

Boris Becker, the retired tennis champion now working with Novak Djokovic, posted: "Let us all pray for realschumacher michael for a full and speedy recovery!!!"