Officers were alerted to concerns of suspected drug dealing in the St Anthony’s Road area on Tuesday (February 6).
Two men seen in a nearby alleyway were subsequently searched under Section 23 the Misuse of Drugs Act.
This search was negative and the pair were sent on their way.
Police then searched a nearby property where they found a large amount of suspected Class A drugs, cash and mobile phones.
“Weapons including a knuckle duster and Rambo style knife were also seized,” a spokesman for Lancashire Police said.
A 16-year-old boy from Nelson, a 19-year-old man from Manchester and 57-year-old man from Preston were arrested on suspicion of possession with intent to supply a Class A drug and money laundering.
All three were bailed while an investigation continued.
If you are concerned about crime in your area, call 101
Independent charity Crimestoppers can also be contacted anonymously on 0800 555 111