Police do not know what caused the tree to fall but are continuing to investigate, said Sgt. Kieran Dwyer.
The accident occurred about 7:30 a.m. at 336 North Broadway in Upper Nyack as the elderly man was driving south in his 2012 Honda Accord. He was alone in the car, police said.
Police found Muhlenberg's car completely covered by the tree and live electrical wires in the area. He was pronounced dead by Rockland Paramedics, police said.
The accident happened in front of the Upper Nyack School, closing the school for the day, said school district officials.
About 117 residents lost power for several hours following the event.
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