Police seized three unlicensed shotguns, £13,000 worth of stolen goods, and more than 100 rounds of ammunition at a property in Hemel Hempstead
Officers carried out a Section 8 PACE (Police and Criminal Evidence Act) search warrant at an address in Three Cherry Trees Lane, Hemel Hempstead.
Four people were arrested in connection with the warrant and remain in police custody at this time.
A police spokesman said: "We are committed to keeping people safe and taking illegal weapons off the streets."
"Please register your valuables at www.immobilise.com so that if they're ever stolen and later recovered they can be returned to you."