(Tigard, OR) -- Officials say 15 people are displaced after an apartment fire in Tigard early Wednesday morning. The apartments are located on 108th Avenue near Durham Road. When firefighters arrived they saw flames coming from the roof of the multistory apartment complex. Residents had been alerting people and when firefighters searched the building no one was inside. The fire damaged six units. The investigation into the cause of the fire is ongoing. One person was treated for a medical issue that wasn't related to the fire. The Red Cross is helping the displaced residents.