The C-17 Globemaster was practicing for an aviation show at Elmendorf Air Force Base when it went down in a wooded area near Anchorage, according to Reuters.
Some eyewitnesses told the news source that the plane was flying low and turning strangely before it crashed.
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"We are confirming four dead," Lieutenant-Colonel Karen Platt, an Air Force spokeswoman, told the news provider.
It is believed that this was the first plane crash involving the Boeing-made C-17 Globemaster since it became the Air Force's newest cargo plane in 1995. The massive craft is 174 feet long with a wingspan of nearly 170 feet. It can also carry 170,900 pounds.
Lieutenant General Dana Atkins said at a news conference that the Air Force is still considering whether or not to proceed with the air show.