According to the fire department, they received the call just after 2 a.m. on Tuesday.
Crews found the home full of smoke. When they searched through the home, they found four people inside.
The genders and ages of the victims are not being released at this time.
It is unknown what the cause of the fire is at this time.
Pueblo Police Chief Sgt. Steve Etienne says they are treating the fire as a criminal investigation.