Local fire officials are warning residents about the deadly dangers of smoking around home oxygen after yet another fatal blaze in the Bay State.

A 68-year-old Plainville man died in a fire last week, according to investigators who found smoking materials and medical oxygen equipment at the scene.

It's the fourth deadly fire in the last month with smoking materials and home oxygen equipment as potential factors.

"Smoking is the leading cause of fatal fires in Massachusetts and across the country," said Plainville Fire Chief Robert Skinner. "We want to remind all our residents that there's no truly safe way to smoke, and that smoking around home oxygen is especially dangerous."

The Plainville Fire Department responded on Friday to the fire at a home on School Street, and spotted heavy fire on arrival.

Firefighters made entry into the single-family home, and found the sole occupant, later identified as Mark Beyersdorfer, who suffered fatal injuries.

The origin and cause of the fire are being investigated by the Plainville Fire Department, Plainville Police Department, State Police fire investigators assigned to the State Fire Marshal's office, and State Police assigned to the Norfolk DA's office.

As with fires in Chicopee, Greenfield, Leominster, and Wakefield, investigators identified smoking materials and medical oxygen equipment within the home as possible factors.

"Friday's tragic fire was the fifth time this year that we identified smoking materials and medical oxygen equipment at the scene of a fatal fire," said State Fire Marshal Jon Davine. "Four of them took place within a month.

"If you or a loved one use home oxygen, please use extra caution with open flames or heat sources," Davine added. "Any fire will burn hotter and grow faster in an oxygen-rich environment."

Over the past five years, six Massachusetts residents have lost their lives in fires caused by smoking on home oxygen. Several others have been badly injured.

The Department of Fire Services offers a pamphlet for residents, caregivers, medical professionals, and firefighters that can help oxygen users stay safe. It can be downloaded from the DFS website at www.mass.gov/info-details/home-oxygen-safety.