At least seven people died Saturday, all of them on the road next to the airport, Police Superintendent Jane Derrick said.
The pilot was pulled from the wreckage of the plane and was airlifted to the Royal Sussex County Hospital, where he remained critically injured, Derrick said.
"It is possible that there are still bodies at the scene and it is important that our search is professional and thorough," Derrick said at a news conference.
The Hawker Hunter jet was flying a loop when it nose-dived about 1:20 p.m. local time (9:20 a.m. ET) onto the road adjacent to the airport near Shoreham in Sussex. The road, the A27, will remain closed while the search is underway, she said.
The air show featured vintage military aircraft and was being put on by the Sea Royal Air Force Association.
