It happened around 5:00 Saturday morning at the Foxcroft Terrace Apartments on the 300 block of North Front Street.
The fire quickly went to a second alarm and was placed under control within the hour.
Initial reports from the scene indicate that residents were able to get out of the building.
One apartment was damaged by the flames while four others suffered smoke and water damage.
The Red cross is assisting 11 families affected by the fire at Yeadon Borough Hall.
Fire officials are still investigating what sparked the blaze.