Originally posted by the Voice of America. Voice of America content is produced by the Voice of America, a United States federal government-sponsored entity, and is in the public domain. Investigators Probe Cause of Alaska Plane Crash VOA News 11 August 2010 This image provided by the Alaska State Police shows the wreckage of the amphibious plane carrying former Sen. Ted Stevens, which crashed into a remote mountainside during a fishing trip, killing Stevens and four others, 10 Aug 2010 Photo: AP This image provided by the Alaska State Police shows the wreckage of the amphibious plane carrying former Sen. Ted Stevens, which crashed into a remote mountainside during a fishing trip, killing Stevens and four others, and stranding the survivors on a rocky slope overnight, 10 Aug 2010 Investigators are expected in the U.S. state of Alaska at the scene of a plane crash that killed the longest-serving Republican to hold office in the U.S. Senate. Former U.S. Senator Ted Stevens was among five victims of the crash late Monday of a small plane ( DeHavilland DHC-3T) near a remote Alaskan fishing village. Among the four survivors is Sean O'Keefe, a former administrator of the U.S. space agency, NASA. He is reported to be in critical condition at an Anchorage, Alaska, hospital. Officials say the single-engine propeller aircraft went down about 525 kilometers southwest of the city of Anchorage. They also say rescue crews did not reach the crash site until dawn Tuesday because of severe weather conditions in the area. The cause of the crash is not known, but flights in the mountainous region can be perilous. Air travel is more common in Alaska than in most U.S. states because it has large expanses of wilderness and few roads outside major cities. President Barack Obama issued a statement Tuesday praising Stevens and extending condolences to the late senator's family and the families of those who were killed along with him in the accident. Flags in Washington, D.C., are flying at half-staff Wednesday in Stevens' honor. The 86-year-old Stevens spent 40 years representing Alaska in the U.S. Senate. He was defeated in 2008 following his conviction for failing to report corporate gifts. The conviction was later overturned because of misconduct by federal prosecutors. In 1978, Stevens was a passenger in a plane crash at an Anchorage airport that killed his first wife, Ann. This is the third plane crash in Alaska in less than two weeks. On July 29, a military plane went down near Elmendorf Air Force Base, killing four people. Just three days later, a cargo plane crashed in Alaska's Denali National Park, killing all three people on board and sparking a forest fire. Some information for this report was provided by AP. .