Four men are under arrest after authorities say heroin and fentanyl was found in a Manhattan apartment.
Investigators say they seized about 20 pounds of a substance they believe to be a heroin/fentanyl mix.
They also found packaging supplies, drug paraphernalia and weapons.
Officials say much of it was taken from a sixth-floor apartment rented by Jesus Perez Cabral in Morningside Heights.
Investigators say they had the building under surveillance for some time and saw two men leave with a bag full of drugs last Friday.
Neighbors say they suspected something was going on in that apartment, but were surprised to find out what it was.
"Every day, I would come home, there is a party all night long. I couldn't sleep well. I was calling 311," said one neighbor.
"Any time you seize 20 pounds of fentanyl mixed with heroin, it's very significant. That much fentanyl in its purest form is enough to kill half the population of New York City," said James Hunt, special agent in charge at the DEA.
The four men are facing several charges, including criminal possession of a controlled substance.