Detectives at East Area Command have executed search warrants at three industrial units in New Road, Rainham.
The intelligence led operation on Monday, 24 January resulted in the seizure of cannabis with an estimated street value of £300,000, a loaded AK47 assault rifle, a pistol and a converted revolver.
In addition, live ammunition, spent cartridges, cash, two crossbows and a quantity of Class B drugs were also recovered.
A 63-year-old man was arrested at the scene on suspicion of drug offences. He was taken to an east London police station and was later released on bail.
Detective Sergeant Owen Morgan of the East Arera Drugs Focus Desk said: “This successful operation although led by the East Area Drugs Focus Desk, was the result of great collaborative team work across the borough, in particular by the Violence Suppression Unit.
“The outcome is the disruption of organised crime that is a blight on communities.
“I have no doubt that the criminality we uncovered during the searches that spanned two days would have negatively impacted an area reaching far beyond Rainham.
“We will continue to combine our resources in order to dismantle and disrupt organised crime wherever we find it.”