Police said officers from the Specialist Enforcement Unit were tasked with investigating the report at Fairfield Recreation Ground on Wednesday, June 8.
They carried out plain-clothes patrols in the area and having identified some suspicious behaviour, a man was detained, searched and was found to be in possession of cannabis, two deals of suspected cocaine, and a large quantity of cash, Sussex Police added.
Officers then carried out a search at an address in West Street, Burgess Hill, where a larger quantity of herbal cannabis was found, including in individual deal bags as well as in a carrier bag and inside a tin of chocolates.
Bags containing white powder suspected to be cocaine, a commando style knife and incapacitant spray were also found at the address, Sussex Police added.
Sussex Police said, following the searches, a 24-year-old man was arrested on suspicion of possession of a class A drug with intent to supply and with acquiring, using or possessing criminal property.
A 26-year-old man linked to the address was arrested on suspicion of being concerned in the supply of a class A drug, and a 25-year-old woman was arrested on suspicion of being concerned in the supply of a class A and class B drug, and with possession of a firearm without a valid certificate.
All three have been released under investigation while Sussex Police’s enquiries continue.