The Portland Fire Department has ruled that the cause of a house fire Saturday at 79 Lincoln St. in the city’s Woodfords neighborhood was the improper disposal of smoking materials.

The two-family, two-story home sustained heavy fire damage to the second floor and heavy water damage to the first floor, city spokeswoman Jessica Grondin said in a statement Monday. The house has been posted as being unsafe for occupancy.

Improper disposal of smoking materials is a leading cause of fires, Grondin said. People should not dispose of cigarettes in vegetation such as mulch, potted plants, peat moss, dried grasses or leaves.

One Portland firefighter suffered a minor injury and was treated at a local hospital before being released, Grondin said.

No other injuries were reported as a result of the fire, which broke out around 9:30 a.m. Saturday.