Drugs, guns and cash were seized during two police raids yesterday.
Large amounts of cannabis were found in a home in Windsor Avenue, North Cheam, and at a big house in the grounds of Lower Pillory Down, next to Woodcote Park Golf Course, yesterday.
Officers also discovered nine guns and bundles of cash which could amount to £10,000.
Three men and one woman, aged in their 30s and 40s, were arrested.
Three were arrested for production of cannabis and one for possession with intent to supply.
They are being questioned at a South London police station and enquiries are continuing.
The operation was carried out by Sutton Police's crime squad following intelligence received from the local community.
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