At least 10 people have been arrested after a series of dawn raids.
Operation Weir saw dozens of police officers swoop on properties across Merton in the early hours of this morning, including a suspected crack den in Streatham Road.
Two men were arrested at the address after police discovered stolen credit cards.
At another address in Mitcham, police seized an illegal loaded pump action shotgun, cartridges, ballistic vests and a large quantity of cocaine.
A further eight people have been arrested in connection with the discovery and other offences including handling stolen property and drug offences.
During a day of action, police carried out sweeps in areas where criminals are likely to stash weapons, ticket checks on transport, increased patrols in criminal hotspot areas, and used automated number plate recognition (ANPR) technology to catch uninsured and stolen vehicles.
To drive the message home, two seized vehicles have been placed outside the Civic Centre in Morden and Wimbledon station, as a warning to criminals.
Darren Williams, Merton’s borough commander, said: “This time of year is traditionally the time when crime peaks – we refer to it as autumn nights.
“The nights are longer and colder and for criminals that is really good because it means it’s darker in the evenings.
“The two worst nights every year are Halloween and bonfire night.
“We have a plan in place around that but started early this year by putting in these pre-emptive raids.”
Residents can help inform and influence the strategy of Merton Council and Merton police in terms of tackling crime by completing a strategic assessment survey - an annual survey which asks residents to highlight key areas of concern in their community.
For more information and to take part visit merton.gov.uk and search for safer Merton consulation.