A GUN seized near the door of a Swansea property marked the start of a Lake Macquarie police raid and the beginning of an investigation into several seized firearms.
Police were assisting sheriff's officers with an eviction order about 12.30pm on Tuesday when they spoke with two women and a man at the property.
All three left without incident, but sheriff officers found a gun near the property's front door.
The discovery prompted police to declare a crime scene and successfully seek a search warrant for the dwelling.
"During the search, officers located and seized more than a dozen firearms, ammunition, knuckle dusters, a sling shot, a crossbow, a jet ski and trailer believed to have been stolen, cash, prohibited drugs and powders believed to be precursors for the manufacture of explosives," NSW Police said in a statement.
The jet ski and trailer were returned to the owner. All the remaining items were taken to Belmont police station, where they are expected to undergo forensic analysis.
Police said an investigation had been launched into the origin of the items. Anyone with information is urged to call Crime Stoppers on 1800 333 000.