A single engine plane crashed into the Columbia River near the Port of Cascade Locks Marina on Sunday morning, but the two occupants were able to swim back to shore safely.  According to the Hood River County Sheriff’s Office, the crash occurred at about 11:45 Sunday morning.  The Sheriff’s Office says witnesses reported seeing the airplane attempt to land at the Cascade Locks Airfield but it appeared as if the landing gear was not down.  The plane then nosed over toward the river and skipped along the water before coming to rest and sinking within the Coast Guard waterway.  The occupants of the plane, a man and a woman from Bellevue, Washington, were able to swim to shore and were transported to a Portland area hospital for treatment of minor injuries.  The cause of the crash has not yet been determined and will be investigated by the National Transportation Safety Bureau.