Police raided homes in Braintree as part of a drugs operation across north Essex.
Warrants were carried out in Bailey Bridge Road and Templar Road, as well as addresses in Clacton, Colchester, Chelmsford, Burnham.
A total of 28 people were arrested and more than 800 wraps of suspected Class A drugs seized as part of Operation Saturn.
As well as the suspected Class A drugs – including crack cocaine and heroin, officers seized 13 quantities of what is believed to be cannabis and a large amount of suspected methadone.
Eighteen search warrants have been executed in the past weeks and 20 people currently remain on police bail after being arrested on suspicion of possession of drugs with intent to supply.
Two suspects were charged with supply, one with possession of cocaine and one with possession of a controlled drug.
A further 31 have also been stopped and searched in relation to possible drugs activity.
Police have been targeting suspected criminal gangs who travel into the area from outside the county.
Detective Chief Inspector John Ross said: “We have definitely made a dent in the supply of drugs in north Essex and in large part this is down to information from members of the public.
“As a result, these gangs are finding it harder to operate in our towns and they know they are not welcome.
“We also know these people are involved in violence such as street robbery and we have seen a significant reduction in this offence over the past six weeks in Colchester, Braintree and Chelmsford.
“If anyone suspects that drug dealing is taking place in their neighbourhoods please call us and we will investigate.”
Chief Superintendent Carl O’Malley, area commander for north Essex, who set up Operation Saturn, added: “No-one in Essex should have to put up with this type of behaviour in their neighbourhoods and I want to tackle the problem head on,” he said.
“I am not willing to tolerate the culture and behaviour of these people.”
Anyone with information about drug dealing or the gangs involved can contact Braintree Police Station on 101 or ring Crimestoppers anonymously on 0800 555 111.