The most recent fire occurred early Monday morning at a home in the 5200 block of Chancellor Street in West Philadelphia, leaving two boys, their mother and their grandfather dead.
The fire marshal said that fire was sparked by an electrical problem.
2-year-old Jayden McClendon, 4-year-old Cincere McClendon, 23-year-old Rishya Jenkins and 68-year-old Seneca "Chuck" McClendon died after being trapped on the second floor when the fire broke out.
Meanwhile, the fire marshal said a blaze caused by cooking was to blame for two deaths in the 1200 block of Firth Street in North Philadelphia.
In that fire, 79-year-old Ardalia Bumpus and her 4-year-old great granddaughter, Nevaeh Bryant, were killed.
The Philadelphia Fire Department again urged everyone in the city to make sure they have working smoke alarms in their home. Anyone who needs a smoke alarm can call 311 for assistance.