Fire investigators Wednesday determined a fire that heavily damaged a west Lawrence apartment Tuesday evening was an accident due to improper discarding of smoking material.

Division Chief Eve Tolefree, a Lawrence Douglas County Fire Medical spokeswoman, said the fire caused more than $200,000 in damage.

Jane Blocher, executive director of the Douglas County chapter of the American Red Cross, said the fire at 2100 Heatherwood Drive displaced two families. The Red Cross provided lodging, meals and clothing to the families. The fire occurred at 5:54 p.m. at Peppertree Apartments complex.

Tolefree said one firefighter was treated at the scene Tuesday evening for minor injuries.

Fire crews initially encountered heavy smoke and fire coming from the two-story residence. Firefighters rescued two dogs.

Because fire began to spread to the attic and roof, firefighters changed to a defensive tactic and fought it from the outside, Tolefree said. It was declared under control at 6:36 p.m.

Tolefree said Wednesday morning that investigators had not yet determined a cause and damage estimate.

Blocher said two people lived on the side of the residence where the fire started, and a family of five that had moved from Texas a few days ago also was displaced.