Investigators say it could take awhile to figure out what brought a plane down in Centre County Saturday afternoon, killing all on board.

Investigators held a press conference Sunday afternoon. They say the plane didn't have a "black box, a voice recorder, in the cockpit. Eyewitnesses report the plane stalled, and then came straight down, crashing near Bellefonte only yards away from the new Centre County Prison.

Investigators say its far too early to pinpoint the cause.

Paul Cox of the National Transportation Safety Board says, "Thats probably the best thing to say is that we have ruled out nothing. We have nothing to lead us in any definitive direction."

Officials believe icing could have caused the plane to crash. An area aviation expert said he is not only fairly certain he knows what happened, but said he also heard some of the last words from the pilot just before crashing.

Just two miles away, thats how far the pilot of the crashed plane had to go before getting to his destination of University Park Airport. At the crash site were members of the Federal Aviation Administration, National Transportation Safety Board and others were on scene for the investigation, but just a mile away, one man says he's fairly certain he knows what happened to the downed aircraft

John Elnitski, Bellefonte Airport owner says, "When the ice forms on the wing, on the leading edge, the ice gets back this way, and then the pilot can see it, but if its clear ice, its hard to see."

Elnitski is talking about icing, not only how it builds up on wings, but also fuel lines. He says, "If your fuel has water in it and ices up, the engine quits, which is probably what happened at the accident. They're going low and slow and then it goes into a spin and down it hits."

Elnitski could hear the pilot's radio transmission Saturday as the plane approached the University Park airfield.

"I heard Mr. Jacober call in for the runway. He didn't give a runway. He was chattery. They called him back and asked for a number. He gave it to them and then asked if his car was there. They said yes. Thats when he was four miles out and then the transmission stopped and I knew something had happened."

Elnitski says the pilots of three planes that landed right beforehand were all talking about icing problems. He also says with ice in the fuel line, and the engine stopping, that could have switched off other systems in the plane, which could be another reason why there was no fire or explosion at the crash scene. Its all preliminary, but Channel 6 will have more in coming days on this tragedy that killed six in this Bellefonte area plane crash.