Inside a house on the block, Homicide Capt. James Clark said, they found the bodies of three men: 25-year-old Keurlin Charles, who lived at the home with his parents, and two other men, whose names have not been released.
Charles was found in an upstairs bedroom with his feet and hands duct-taped behind his back. Another man was found similarly bound in the living room, along with a third victim who had not been tied up.
All three had been shot in the head.
Police believe the third man walked into the home after the shooters had arrived there, Clark said.
"He walked in and was put on the ground and also shot in the head," Clark said.
Clark said investigators are looking for possible connections between Thursday's shootings and the Jan. 19 killing of Donna Walter Muller and her son, Richard, in their home on the 300 block of Stevens Street.
Muller and her son were found with pillows over their heads, Clark said.
One of the victims Thursday also had a pillow placed over his head, he said.
Police will analyze ballistics evidence to see if the guns used in both shootings are a match, Clark said.
Neighbors described a scene of chaos on Martins Mill on Thursday night.
Aleida Hernandez, who recently moved into a house down the block, said she saw a woman running into the street screaming and crying as police arrived.
"We were family," she yelled, according to Hernandez.
More than a dozen squad cars arrived moments later, she said.
The family members in the home kept to themselves and were not well-known on the block, neighbors said.
Inside the home, police found parts of the living room and the second floor ransacked.
"Whoever did this was looking for something," Clark said. "It was horrific."
Detectives were on the block Friday afternoon, canvassing neighbors to ask if they had seen any suspicious activity in the days before the slayings.
A $60,000 reward for information leading to an arrest and conviction has been offered in the case.
Anyone who noticed anything unusual in the area, or has information on the killings, is being asked to call the Homicide Unit at 215-686-3334.