ROCKFORD, Ill. (WTVO) — Carless smoking was determined as the cause of a fire at a four-family apartment in Rockford on Monday night.

According to the Rockford Fire Department, the occupant of an apartment building in the 2300 block of Hecker Avenue called 911 around 10:35 p.m. after seeing smoke coming from under a window sill in the living room.

All the occupants were able to escape the structure before firefighters arrived, and one man was seen spraying water on the wall of the building with a garden hose.

Firefighters said they found fire in the wall cavity of the apartment that extended down to another unit on the first floor.

It took 20 minutes to bring the fire under control.

A fire investigator said the fire was caused by discarded smoking materials.

Two of the families in the building had to be relocated by the Red Cross. No one was injured.

The cost of the damage was estimated at $35,000, authorities said.