Donald MacKenzie says he woke up to the sound of screaming early Saturday morning.
"I saw my neighbor was literally naked, running up and down his driveway with a hose and his house was engulfed in flames," said MacKenzie.
He called 911, grabbed a ladder in his yard and helped rescue a man from the second floor of a home in Oyster Bay.
The homeowner and an Oyster Bay firefighter suffered burns but are expected to survive.
A male tenant was treated for smoke inhalation.
Nassau County Arson Bomb Squad Detectives along with the Nassau County Fire Marshal determined the fire to be accidental.