I can't link URL's for some reason, however if you click through, an eye witness at the airport said the following:
“I was standing near the terminal building and I saw him starting to head west and his gear was going down and he was just looping back to land,” the man said. “His plane started to roll and at first I thought he was doing a barrel roll, but then I realized he was way too close to the ground to be doing a barrel roll. His plane just nosed on over and went straight into the ground almost perfectly vertical.
“There was a huge splash of dust, but no fire started or anything like that. I never heard the engine rev up or anything, so there’s not much he could have done to pull out of it.” The witness estimated the plane was 400-500 feet in the air when it began to encounter problems.