A drugs farm was discovered close to a Fylde primary school.
Police officers executed a search warrant on Friday on Mayfield Avenue, St Annes, discovering a haul of cannabis and cultivation equipment.
The two men, aged 40 and 19, and a 15-year-old boy have been bailed until December 22. A 34-year-old woman has been bailed until December 15.
PC David Payne said: “All four were arrested on suspicion of drugs offences.
“The investigation is still ongoing to determine the exact amount of cannabis found.”