SAUK RAPIDS, Minn. (AP) - Federal investigators have been unable to determine why a small plane crashed into a house in Sauk Rapids last year, killing the pilot and a German foreign exchange student who was a passenger.

The report by the National Transportation Safety Board discusses the possibility that the cockpit's canopy opened during the flight. But the plane was too badly damaged to test the canopy and its latching mechanisms.

The crash killed the pilot, 60-year-old Scott Olson, and 16-year-old foreign exchange student Alexander Voigt. A man in the house jumped from a second-floor window and was unhurt.

The report also says the effects of wake turbulence from an Allegiant Air flight that was in the area at the time of the crash could not be determined.