A man was arrested in Brigg on suspicion of possessing an imitation firearm after an incident on the evening of Saturday January 4.
Humberside Police were called at 11.55pm on Saturday with reports of a number of men exiting a car on Buckingham Street, Scunthorpe, with what was believed to be a firearm.
They left the area in the car.
Armed response officers were deployed at midnight of Sunday January 5 to conduct an area search.
The car was followed to Brigg by the police helicopter after being sighted by divisional patrol, the three occupants were then challenged by armed response officers.
They were arrested on suspicion of firearms offences.
Before being stopped by police the helicopter sighted a further man exiting the vehicle in Brigg before it was stopped, following further enquiries this man was arrested.
A 23-year-old was arrested on suspicion of possessing an imitation firearm with intent to cause fear of violence, possessing ammunition for a firearm without a certificate and possession of cannabis. He has been released on bail pending further enquiries.
Three men aged 20, 21 and 23 have been unconditionally released.