SAN FRANCISCO, Aug. 10 (Xinhua) -- Former U.S. Senator Ted Stevens and former NASA Administrator Sean O'Keefe were among the nine passengers aboard a plane that crashed in the U.S. state of Alaska, according to U.S. authorities and media reports on Tuesday.
Five people were believed dead in the crash on Monday evening, but the status of Stevens and O'Keefe were not immediately known.
Guy Hayes, spokesman for the Alaska National Guard, earlier said that the crash site was 32 km north of Dillingham. A passing- by aircraft saw the wreckage Monday evening and informed the Guard.
"Reports are that 5 of the 9 persons on board died in the accident," the National Transportation Safety Board (NTSB) said in a statement released Tuesday morning
The NTSB said that it has launched an investigation over the crash, but did not provide further details.
Sean O'Keefe, the ex-NASA chief and now the CEO of defense contractor EADS North America, was confirmed to be aboard the plane.
"Sean O'Keefe, EADS North America's CEO, was a passenger on a private aircraft that crashed in Alaska last night," Guy Hicks, EADS North America spokesperson, said in a written statement Tuesday.
"Local authorities are reporting that there are survivors and a rescue operation is underway," Hicks added.
Friends of former Senator Ted Stevens feared he was aboard the plane, according to reports by Anchorage Daily News, a local newspaper in Alaska.
The downed plane is a 1957 Dehavilland DHC-3 Otter registered to a local communications company, the Federal Aviation Administration said.