Officers responded to a 911 call reporting someone screaming in front of the home in the 6300 block of Martin Mill Road just before 3:30 p.m.
Police arrived to find the house ransacked and three men in their 20s all were fatally shot in the head.
All three men were pronounced dead at the scene.
Two of the bodies were found tied up on the first floor, and the third victim was found in an upstairs bedroom, police spokesman Lt. John Stanford said Thursday night.
He said investigators are trying to determine if the triple slaying is the result of a botched home invasion robbery.
"It appears at this point that two people are tied down, the house is being ransacked," he said, "and a third individual walks in on the robbery taking place and there is some type of struggle."
The preliminary investigation suggests that the person who apparently walked in on the robbery was killed first upstairs and the two tied up downstairs were killed after that, Stanford said.
He said authorities were working to identify the victims and determine who among them were visiting the home and who lived there.
No arrests have been made. Witnesses told police they saw two men believed to be in their 20s running from the scene.
Investigators are canvassing the neighborhood and looking for any homes or businesses that may have captured the fleeing suspects on surveillance video, Stanford said.
Anyone with information is asked to contact Philadelphia Police.