Seven kilos of drugs were found in the Hillside apartment complex at 6060 Crescentville Road on Wednesday, police said.
During a Friday morning news conference to announce the bust, investigators called it one of the city's largest herion seizures to date.
The bust was a result of a two week stakeout.
Investigators said it all began when the FBI got a tip out of the Lehigh Valley that there would be a home invasion robbery at an apartment.
Authorities made an arrest in that case, which led to three more arrests and the seizure of the heroin.
"Look at the heroin here. It's going to be broken down and sold in $10 packages. That's over 100,000 drug transactions," said Chief Insp. Scott Small.
Police say this will have a major impact on drug trafficking in Philadelphia.
"Heroin is a very big problem and it appears to be an increasing problem," said Insp. Small.
No one can speak on the horrors of heroin addiction like recovering addicts. William Truitt has been clean for two years, and he says this seven kilo bust will dent the street supply for a while. However, Truitt says, the market and will to supply is too strong.
"This has happened before, maybe a year or so ago, where there was a big bust. It dries up for a little while. It does make a dent in it, but it will be back to flowing in a month or two," he said.
Four people have been arrested, and sources say they all come from the same town in the Dominican Republic. Furthermore, all four have arrest records, police said.
Police have not released their names or pictures, citing the ongoing investigation.