At a news conference on Wednesday afternoon, police released more details about the killings of 17-year-old Christopher Malcolm and 13-year-old Rohan "Sonny" Bennett.
It was around 7:30 p.m. Tuesday when police were called to the 1300 block of Westbury Drive in the Overbrook Park neighborhood.
Capt. James Clark said that an unidentified male came to the home with the intention of making a drug transaction.
"He was having some type of discussion with the two teenagers; something at that point triggered the chain of events where he pulled out a gun," Philadelphia Police Captain James Clark said.
Police couldn't say what exactly happened, but the man pulled out a gun and shot Malcom in the living room. Malcolm later died at the hospital.
The gunman also shot Bennett, who managed to run into the basement. He was pronounced dead at the scene.
Witnesses told police they saw a man fleeing the home with a large bag. He was only described as a man with a light complexion wearing a blue shirt.
Investigators said they have a 'person of interest' in this case, but released no details about that individual.
As police searched the home, they allegedly found $102,000 in cash, more than 1,700 illegal prescription pills including Oxycodone, Percocet, Xanax and six large bottles of Codeine. Police say they also found a small amount of marijuana.
Most of the drugs and cash were found in the bedrooms of the boys' parents, police said. Those parents were being questioned and are likely facing drug charges.
At this point, investigators say it appears that Bennett and Malcolm, a new father who has a criminal narcotics record, were involved in the selling of drugs in an operation founded by their parents.
Meanwhile, by Wednesday morning, loved ones began forming a memorial outside the home.
"Just a really unfortunate situation," said neighbor Simaj Johnson. "I'm very sorry, very upset about what happened."
"I don't know what it was over, what it was about, I don't care what it was about. An innocent life, another life in this city, is being taken," said friend Darius Daniels.
Anyone with information is asked to contact Philadelphia police at 215-686-TIPS (8477), text a tip to PPD TIP or 773847, or through phillypolice.com.