Hatch saved Austin, but his other children -- Lindsay, 11, and Ian, 5 -- died along with his wife, Julie, 38.
"His wife and two children were in flames and he was never able to reach them," Bojrab said. "Steve reached over to his son who was sitting in front with him and tossed him out the window to save his life."
Beilein said in a statement that the university was saddened to hear about the tragedy affecting the Hatches. "Austin needs as much support right now as possible and I know he will be in the thoughts and prayers of the Michigan family during this difficult time," he said.
Canterbury School said in a statement Saturday to "keep Austin and his family in your thoughts and prayers."
Bojrab said Stephen Hatch had planned to go to Spain to celebrate his parents' 50th wedding anniversary with the rest of his family, but canceled the trip to spend time with Austin and his adult stepchildren.
"Steve was a very big family man," Bojrab said.
Another of his passions was Smith Field Airport, a small, historic airport near Fort Wayne. Bojrab said Hatch led a campaign several years ago to save it and bought the Smith Field Service Center and its flight school.
"He saved the property from being developed commercially," Bojrab said, adding that Hatch was instrumental in getting it on the National Register of Historic Places.
NTSB spokesman Keith Holloway said investigators were on the scene Saturday and would be examining the aircraft, interviewing witnesses and requesting air traffic control communications and radar data. He expected a preliminary report within 10 days and a final report determining a cause within 18 months.
AP Sports Writers Cliff Brunt in Indianapolis and Noah Trister in Detroit contributed to this report.