A plane carrying former US Senator Ted Stevens and former head of NASA Sean O'Keefe has crashed in Alaska.
Local television is reporting that Mr Stevens died in the crash in his home state of Alaska, but that has not been confirmed.
The fate of Mr O'Keefe is not yet known, EADS and a congressional source said.
Five people died when the small plane crashed last night in a remote part of Alaska, federal aviation officials said.
'Local authorities are reporting that there are survivors and a rescue operation is under way,' EADS North America spokesman Guy Hicks said in a statement.
Mr O'Keefe, 54, is the former head of NASA and worked for Mr Stevens for many years in Congress on annual spending matters including defence work.
His son was also aboard the plane, according to the source.
The group was on a fishing trip in the remote part of the state, according to the congressional source, adding that the plane either crashed by a lake or into the water.
Mr Stevens, a Republican, was a former chairman of the powerful Senate Appropriations Committee and a strong supporter of robust US defence budgets.
The single-engine propeller plane, a DeHavilland DHC-3T, crashed about 16km northwest of Aleknagik, Alaska, according to the US National Transportation Safety Board.
There are conflicting reports about how many people were aboard the plane.
Federal safety officials said early information indicated nine people were aboard and up to five were killed, while another source close to the matter said only eight were aboard and five were dead.
Bad weather was hampering rescue efforts but a private medical team was on the scene after being dropped off by helicopter from nearby Dillingham, Alaska.
