At around 3:40 p.m., police were called out to the 1000 block of South 54th Street for the report of a shooting.
When they arrived they found a 44-year-old man suffering from a single gunshot to the back of the head.
He was pronounced dead at the scene.
No arrests have been made.
At about 20 minutes earlier, police were called to the 900 block of Master Street in North Philadelphia for a report of another shooting.
Investigators are also trying to solve three earlier homicides. The first of which happened in the city's Mayfair section. In that case, a man was found shot multiple times inside a car on the Roosevelt Boulevard.
The second murder occurred when a man was shot while exiting a Chinese fast food restaurant in the Brewerytown section of Philadelphia.
In the third homicide, police found a 29-year-old lying in the middle of the street in Summerdale at around 1:00 a.m. He was pronounced dead a short time later.