Eight men and two women suspected of supplying crack cocaine and heroin have been arrested in dawn raids across east London, Essex and Kent.
More than 100 officers took part in the simultaneous warrants on Wednesday, the Metropolitan Police said.
During searches of 10 properties, a firearm, Class A drugs, £15,000 in cash and £30,000 in high-value items, such as Rolex watches, were seized in Newham, Enfield, Tilbury and Ashford.
The suspects, aged between 21 to 57, are detained on suspicion of conspiring to supply crack cocaine and heroin.
A police spokesman said all remain in custody at an east London police station and enquiries are contine.
Their arrests result from a nine-month investigation into the inner workings of a large gang based in Newham which is linked to alleged criminality in east London and surrounding areas.
Detective Sergeant Danny Cooper, who led the investigation, said: “We do not tolerate violence in our communities and we will be relentless in tracking down those responsible for causing it and will bring them to justice.
“We take the harm these people are causing seriously and know that removing them from our streets is incredibly important to Londoners and to their safety.
“We will continue to use all available tactics to identify and arrest those responsible for committing these crimes.”
Scotland Yard added: “These arrests highlight the Met’s commitment as part of A New Met for London to tackle crimes that affect communities most, taking violent drug dealers off the streets.”
