Lawrence-Douglas County Fire Department officials are still unsure what caused a small fire at an apartment complex at 2430 Crestline that damaged two mattresses.

Doug Green, division supervisor for Lawrence Fire, said the fire department received a phone call around 11:30 a.m. reporting the smell of smoke on a first-floor apartment.

Upon arrival, firefighters discovered two smoldering mattresses. The mattresses were removed and doused. No one was injured and other than smoke damage in the bedroom, structural damage was minor.

Green said an investigator was being called to the scene to determine the cause. He said the fire department was hoping to have the cause for the fire determined by Tuesday morning.

Erika Fisher and Brianna Rank, who live in the upstairs apartment, were the first to call emergency workers.

Fisher said she was in bed when she began to smell smoke. Not thinking anything of it, she decided to go back to bed when she began to hear faint beeping noises.

“We went downstairs and saw the hallway was filling up with smoke,” Fisher said. “Then she (Rank) dialed 911.”

Green said the apartment’s tenants were not home at the time of the fire.