Tenants had to stay out of the building for more than an hour. (CBC)

Fire investigators say an early morning fire in an apartment building started in an unoccupied unit, and the cause is suspicious. More than twenty people were forced from their apartments early Tuesday morning after a building on Evans Avenue filled with smoke.

Firefighters evacuated the 4-storey brick building around 4:15 a.m.

They found a small fire in one of the apartments and were able to put it out quickly.

One Halifax Regional Police officer rushed into the building to wake a hearing impaired tenant, but the tenant was not home. The officer was overcome by smoke and was taken to hospital for assessment. He was later released.

Tenants were out of the building for more than an hour. A Metro Transit bus was brought in to provide them with a warm place to wait. The Red Cross was also on the scene to help out.

Everyone was allowed back in the building just before 6 a.m.

The investigation into the cause of the fire has been turned over to police.