Seven people have been arrested in dawn raids as part of a crackdown on an alleged "county line" drug dealing network that sent heroin and crack from east London to Suffolk.
More than 80 police officers swooped in Newham, Essex and Suffolk in the early hours of Tuesday and held five men and two women aged between 19 and 39.
Gangs operate so-called county lines by receiving calls from customers in far flung places and using teenage couriers to take them the drugs.
Often a vulnerable person in the area will have their home taken over by the dealers to store and sell drugs.
It is claimed that a gang based in Newham, which had been monitored by police since March, sent heroin and crack cocaine to the Ipswich area.
During the raids three men were arrested, two aged 19 from Newham and one aged 25 from Tottenham, and searches were carried out at five addresses in Newham, plus one in Haringey.
In Suffolk police searched properties in Bond Street and Main Road, Ipswich, and arrested a 39-year-old man and two women, aged 33 and 37, all from the town.
The final suspect, a man aged 25, was arrested by Essex Police in Falcon Avenue, Grays.
Investigators also seized a 10-inch hunting knife, a stolen moped, cannabis and the mobile phone believed to have been used for running the county line.
Detective Inspector Jim McKee from Scotland Yards Trident gangs unit said: "Those who run county line drug dealing networks are responsible for exporting violence to towns outside of London and we are committed to relentlessly pursuing and disrupting them.
"We believe the disruption of the drug dealing gangs could have a direct impact on reducing the level of violence in London."
Speaking to journalists on Tuesday, Detective Superintendent Richard Turner said the Trident command has worked with police in Newham since July to try to reduce violence in the area, where he said warring gangs were the main cause of bloodshed.
He said: "We've been looking at different groups that we believe are responsible for the violence there, and we've been looking for opportunities to reduce that violence by arresting people for whatever criminal activity we find that they have committed, be that firearms offences, violence offences, or as in this case drugs supply offences, in order to try and reduce the violence that we see on London streets.
"And equally in this case reduce the suffering and the misery that goes hand in hand with Class A drug dealing and the exploitation of those involved in that as well."
The operation comes amid a surge in violent crime.
Nationally, the number of homicides went up by 9% in 2017 compared with the previous year, up by 54 to a total of 653, when cases linked to the Hillsborough disaster and last year's terror attacks were excluded.
Violence against the person and crimes involving a knife were both up by around a fifth, and gun offences went up by 11%.
In London Scotland Yard has launched more than 70 murder investigations so far this year, compared with a total of 131 last year.