Update, 4:55 p.m.: First Assistant Fire Chief Dave Williams said that upon coming to the scene of the fire, firefighters heard an explosion at the site, believed to be oxygen tanks.
"We started with an aggressive offensive attack, but due to the volume of the fire, we had to pull back and fight it from the outside," Williams said.
He estimated that about a quarter of the home was damaged by the fire itself, with the rest likely sustaining heavy smoke damage.
The Port Jefferson Fire Marshal and Suffolk County Arson Squad are investigating the fire.
Original story: Several fire units responded and knocked down a house fire on Red Barn Lane that engulfed the home in smoke around 3:30 p.m.
Port Jefferson Fire First Assistant Chief Dave Williams noted that two people and a dog made it out safely.
According to Suffolk County Police, a call reporting a "house full of smoke" came in at 3:33 p.m. at 4 Red Barn Ln. A police spokesman said the house was evacuated safely, and Suffolk County Arson Squad was called to the scene.
Units on hand include: Port Jefferson, Setauket, Terryville, and Mt. Sinai Fire Departments; Port Jefferson Volunteer Ambulance; Port Jefferson Constable; and Suffolk County Police.
Christine Sampson contributed to this report.
Check back with Port Jefferson Patch as more information becomes available.