Honolulu Fire Department investigators have classified the cause of a three-alarm condo fire in the Keeaumoku Street area over the weekend as undetermined.

Honolulu Fire Capt. David Jenkins, spokesman of the fire department, said there’s insufficient information to identify one specific cause of the fire.

At about 10:30 a.m. Sunday, approximately 50 firefighters responded to a fire on the third floor of a residential building located at 620 Sheridan St. Residents in the 24-unit building were evacuated. Firefighters brought the fire under control in about 15 minutes and extinguished it shortly after.

Emergency Medical Services treated and transported a 49-year-old man and two women, ages 58 and 88, to a hospital in stable condition due to smoke inhalation.

Several apartments were damaged by the fire and the entire building was considered unsafe for residents to occupy overnight due to smoke damage and heavy fumes.

The American Red Cross is assisting residents and most residents will be allowed to return to their apartments by this afternoon, according to Jenkins.

Damage to the structure and its contents is estimated at $150,000.