Five fire departments responded to the scene as well as 19 Emergency Medical Services agencies, police said.
The cause of the accident hadn't been determined, and no charges had been filed related to it. Investigators were working to sort out the sequence of events that led to the accident, on an isolated stretch of road on the rural part of eastern Long Island, Fallon said.
"Anybody rolling up on this scene you would think there would be definitely more than just one fatality," said John Mirando, chief of the Ridge Fire Department. "It's just lucky that it's only one, but it could have been a lot worse."
Driver Danny Gershonowitz told Newsday that he was ahead of the accident when he saw two cars stop on the road shoulder.
"The gentleman to the right of me went down to the ground and was praying. When I looked in my rear view mirror, there was smoke and flames coming out," he said.
He said he and others got the attention of the truck driver and helped him as he climbed out of his smoking vehicle.
"Pretty soon, the whole front of the truck was engulfed in fire, and that's when people started backing away," he said. "The police came and asked everybody to run and get out of the way, because I guess they thought it would explode."