AirMed One from Hackensack University Medical Center flew the man to St. Barnabas Hospital in Livingston (UPDATE: He died there on Tuesday, Dec. 29, authorities said).
"It was an intentional act," Detective Lt. Edward Kane told Daily Voice.
Officers who responded the northeastern part of town just after 3 p.m. found "his condition deteroriorating" before their eyes, the lieutenant said.
He had severe burns on his head, face, chest, and arms, Kane said.
The Upper Saddle River Volunteer Ambulance Corps, the Upper Saddle River Volunteer Fire Department, Valley Hospital paramedics also responded.
Click here to follow Daily Voice Mahwah-Ramsey and receive free news updates.