SPOKANE, Wash. -

Spokane firefighters were called out to an apartment fire on the 2900 block of East Diamond Avenue in Hillyard late Tuesday night.

Just after 11 p.m., firefighters received several reports of smoke and flames at a five-unit apartment complex. Three of those units were occupied at the time of the fire.

Firefighters said the fire started in the southeast corner of the house on the lower level. According to one of the residents, that was one of the units that was supposedly vacant. However, the resident had seen people coming and going from it throughout the week.

Firefighters said when they arrived on the scene, the fire was already very advanced. It had spread from that unit, to the attic and eventually the roof collapsed. The building was fully engulfed in flames and it was threatening the neighboring buildings on both sides. Crews couldn't attack the fire because it was so out of control and they had to go into "defense mode."

Firefighters were able to put the fire out just before 3 a.m. It didn't spread to neighboring buildings and everyone was able to escape safely.

A woman, her boyfriend and her two children were taken to the hospital for minor smoke inhalation and they were released around 5 a.m. Wednesday. Another adult was treated at the scene for a burn to his hand. A firefighter hurt his arm while he was doing a search of the second floor.

All of them are expected to be OK.

Red Cross has set up a shelter at Rogers High School for the victims. There are a total of 26 people at the temporary shelter. There were 14 people living in the building that caught on fire. There are also 12 neighbors at the temporary shelter because they are without power.

Red Cross said the shelter won't be up all day. Once the power is restored, the neighbors will return to their homes. The people who were living in the apartment complex that caught on fire will be set up in a local motel.

Firefighters said they expect to be at the scene investigating the fire until midday Wednesday.

The second flood and attic had significant fire damage, while the rest of the building had a lot of smoke and water damage. Firefighters estimate that there was $70,000 in damage.

No word yet on what caused the fire.