The incident happened Sunday around 1:30 p.m. on Saylors Pond Road near Route 537 in Springfield Township, Burlington County.
Police said 79-year-old Roger N. Lippincot was outside his Jobstown home riding his lawn mower when somehow it caught fire.
Investigators say Lippincot, a retired Springfield Township firefighter, tried to put the fire out himself. He suffered severe burns when the lawn mower combusted, and he was pronounced dead at the scene.
His former fire company in Springfield Township posted a tribute to him on their website Sunday night.
Springfield Township Fire Company Chief Brian Kokotajlo says Lippincott served as the township's emergency manager coordinator and taught at Burlington County's fire academy.
Kokotajlo says Lippincott was the second retired Springfield Township firefighter to die in a fire-related accident within the last two years.
State Police Sgt. 1st Class Gregory Williams says the major crimes, arson and bomb units are continuing to investigate the incident.
Information from the Associated Press was used in this post.