A BBC spokeswoman said: "The incident happened quite recently and the focus of our attention is on Richard at this stage. "We will make further details known as soon as they are available."
Inspector Mike Thompson, of North Yorkshire Police, said officers were dealing with the incident at the airfield north-east of York. He said:
"At 5.45pm (on Wednesday) evening we received a report via the fire service of a male person trapped in what was described as an overturned jet car which had been driven on the airfield. The male occupant has received serious injuries and has been airlifted to hospital at Leeds."
He said no further details were available at this time. Hammond was in a "critical" condition at Leeds General Infirmary, a hospital spokesman said.
The 36-year-old presenter was in a special neurological unit. A North Yorkshire Police spokesman confirmed the accident happened on Elvington airfield, which is seven miles to the south-east of the city.
Apparently Hammond was attempting to break the British land speed record. Former firefighter Dave Ogden, who runs private firm Event Fire Services, was one of the first people at the scene of the crash. He said:
"We were down there with Top Gear who were filming him trying to break the British land speed record. On the previous run, the car had just gone over 300mph but I am not sure if it had broken the record. They had just done one more run and were planning to finish when it veered off to the right. One of the parachutes had deployed but it went on to the grass and spun over and over before coming to a rest about 100 yards from us."
I can only hope that Mr Hammond's injuries are not life threatening, Top Gear has been the fundemental Car Show and has taken the world by storm. Mixing car reviews with entertainment with a perfect balance, Top Gear has found millions of fans around the world. The show airs, one season behind, on SBS here in Australia.