Detectives from Cardinia Crime Investigation Unit have arrested a man and seized six firearms today as part of an investigation into explosions in the Pakenham area this year.
His arrest follows a series of explosions in the vicinity of Pakenham Creek between August and September.
With assistance from the Bomb Response Unit, detectives executed a search warrant at a Pakenham address about 7am on Friday 15 October.
Police arrested a 35-year-old man before seizing explosive materials and items.
Officers also discovered six firearms, including two homemade firearms and an imitation firearm, and a large amount of ammunition.
The Pakenham man is currently assisting with enquiries.
The investigation remains ongoing.
Anyone with information or CCTV is urged to contact Crime Stoppers on 1800 333 000 or file a confidential report online at crimestoppersvic.com.au.