The retired seven-time Formula One World Champion was injured on Sunday when he was skiing with his son at a resort in Meribel on the French Alps.
Reportedly, Schumacher fell and struck his head on a rock while skiing. According to reports, he was wearing a helmet, and was still conscious when emergency workers arrived, but was in shock and agitated.
Even though Schumacher was wearing a helmet, he sustained a head injury that required immediate surgery to relieve pressure on his brain after his transfer to Grenoble University Hospital Center.
A scan showed that he had suffered a cerebral contusion, and according to Jean-Francois Payen, chief anesthesiologist at the Grenoble, France hospital, Schumacher would have most likely died had he not been wearing a helmet.
Doctors are unable to comment on a prognosis, saying "We cannot predict the future for Michael Schumacher. He is in a critical state in terms of cerebral resuscitation. We are working hour by hour.”
German racing driver Schumacher, who turns 45-years-old on Friday, is considered the most successful driver in Formula One history with 91 victories. He also made an appearance on BBC's "Top Gear" as The Stig in 2009.
In a statement, Schumacher's family thanked doctors for doing "everything possible to help Michael" and people from around the world for "the outpouring of support".