Pueblo Fire Crews responded to a structure fire at 111 Midway Avenue near Abriendo Avenue.
The fire started around 6 a.m. and has reportedly displaced at least five families in the complex.
The fire was contained to the attic of the four-plex. Emergency crews had to use special methods to attack the fire.
"The roof could come down, the ceiling come down, become involved the floor could become involved in the flames, trapping them on the second floor," said Assistant Fire Chief Shawn Shelton. "Our best tactic is to attack it from the outside and darken it down and then go in from the inside."
Everyone inside made it out safely. A cause has not been determined.