Cambridge, Mass. ? A former MIT professor and multimillionaire businessman who has been praised for his riveting lectures but also known for his family disputes was ambushed outside his office and shot multiple times, authorities said Saturday.

John J. Donovan was taken to Massachusetts General Hospital after the shooting Friday night and later released, hospital spokesman Arch MacInnes said Saturday.

The 63-year-old founder of consulting firm Cambridge Executive Enterprises was shot several times, and it wasn’t immediately clear why he wasn’t more seriously injured, police spokesman Frank Pasquarello said. He didn’t know if Donovan was wearing a bulletproof vest but said a belt buckle may have helped saved his life.

“There was something in his belt buckle – a bullet or a fragment,” Pasquarello said.

Donovan described the shooter only as “a white male,” Pasquarello said.

The former professor called 911 himself after he was shot while in a parking lot outside his company’s office near the Massachusetts Institute of Technology campus, Pasquarello said. He said Donovan was found inside a white minivan. The parking lot is gated and in an isolated area.

Police were investigating but had not made any arrests Saturday or determined a motive, Pasquarello said.

Donovan, who is worth an estimated $100 million, has been in a dispute with his children, claiming they are trying to force him out of his home.