The men have all been arrested and charged on suspicion of supplying Class A drugs, including heroin and crack cocaine, in the Preston area.
On Tuesday (October 8) police arrested Abrar Ahmed and Yasir Ali in Tulketh Road.
Ahmed, 23 and Ali, 22, both from Manchester, were subsequently charged with Conspiracy to Supply Class A drugs and appeared before Preston Magistrates' Court on Wednesday (October 9)
On Thursday (October 10) police executed a number of warrants in Salford and Longsight in Manchester.
Officers arrested Shavon Morrison, 21, of Claremont Road, Manchester and Richard Mushonga, also 21, of Medway Close, Salford.
They have been charged with Conspiracy to Supply Class A drugs and appeared before magistrates in Preston this morning (Friday, October 11)
All four have been remanded in custody.
Police said a significant quantity of Class A drugs, including heroin and crack cocaine, had been seized from the drugs gang.
Detective Chief Inspector Steve Holgate, of South Police, said: "We will continue to tackle organised crime groups responsible for the exploitation of adults and children using the county lines model across a number of force areas.
"Our commitment to disrupting and dismantling these groups and this type of criminality alongside our partners is a priority and we will continue with these efforts to ensure we keep our communities safe.
"My message to these gangs is clear, you are not welcome in Lancashire and if you continue to conduct your criminal activities in this area then expect to be identified and arrested.
"The safeguarding of children and vulnerable adults is a priority for us all and we continue to focus our efforts on bringing anyone who exploits such individuals to justice.
"I would also urge our communities to work with us on identifying those responsible for this type of activity so that we can continue to keep our communities safe.
"Intelligence from members of the public is key in operations like this and I would appeal to anyone who has information that could assist, whether that be concerns around children, premises that are being used by such groups or indeed information about those responsible to come forward."