An investigation is under way after a firearm was recovered from a car.
Police were called after a motorist on the M65 reported someone in a red Fiat Punto had pointed what they thought was a firearm towards them.
The incident happened between junctions 7 and 8.
The Fiat Punto left the M65 at junction 8 and headed towards Bury on the A56.
Police there then received reports of two cars driving at speed near Bolton Road in Bury.
When officers attended they found a Fiat Punto and a black Audi A4 had crashed in Croston’s Road.
A firearm, believed to be a black handgun, was recovered from the Punto.
A 26-year-old woman from Rossendale has been arrested at the scene on suspicion of possession of a firearm.
Two men, aged 18 and 22 from Blackburn, were also arrested at the scene on suspicion of possession of a firearm.
Another two men, aged 33 and 37 from Blackburn, were arrested at the scene on suspicion of affray.
They are all currently in custody and being interviewed by detectives from Lancashire who are leading the inquiries.
The firearm has been sent for forensic analysis.
Detective Inspector Mark Vaughton, of Blackburn Police, said: “We believe that the occupants of the Fiat Punto and the Audi are from the East Lancashire area and are known to one another.
"While we have recovered a firearm there is thankfully no suggestion that this was discharged at any point during the incident.
“Having said that we are treating this extremely seriously and we are working closely with our colleagues in Greater Manchester Police to progress this inquiry.
"Investigations are on-going and I would appeal for anyone who witnessed either of the two vehicles at any stage during this incident to get in touch with us.”
The incident happened at around 4pm yesterday.
Anyone with information should contact police on 101 quoting log number 775 of Wednesday, January 22nd or Crimestoppers on 0800 555 111.