His name was being withheld pending notification of next of kin.
A firefighter refused medical attention for a cut sustained battling the first-floor Rutgers Lane blaze, which broke out in the Rutgers Village Apartment Complex just after 12:30 p.m. and severely damaged two units, they said.
The main body of the fire was knocked down by Parsippany and Lake Hiawatha firefighters within a half-hour, after which they summoned investigators.
The Morris County Prosecutor’s Office Arson and Environmental Crimes Unit was investigating along with Parsippany police and fire inspectors.
The Morris County Sheriff's Crime Scene Investigation unit collected evidence.
"The cause of the fire is undetermined," Morris County Prosecutor Fredric M. Knapp said Sunday night. "However, there is no indication that the fire was intentionally set."
Mutual aid responders included Boonton, Montville, Morris Plains, Mount Tabor and Whippany firefighters.
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