Thames Valley Police is investigating after gunshots were fired from a car in Aylesbury.
Officers were called to an incident in Church Square, during which it is believed a gun was used.
There were no injuries following the firearm discharge.
Following this, both vehicles drove away, and later collided with one another in nearby Hampden Gardens.
A 26-year-old man was then assaulted, resulting in him being taken to hospital with critical injuries, where he remains.
The firearm is not believed to have been used during the second incident and officers are attempting to locate it.
We have been conducting a thorough investigation into this incident and have made an arrest in connection with it. Our officers are carrying out a full comprehensive investigation which will continue.b I would like to appeal to anyone that may have information which could help with my investigation to contact police. I would also like to appeal for anyone who may have seen a silver coloured BMW 330i or a silver Nissan Almera in the area at any time prior to this incident. Reports can be made by calling 101, and quoting URN 1618 24/5. You can also make a report online, or you can call Crimestoppers anonymously on 0800 555 111.
A 54-year-old man has been arrested on suspicion of attempted murder in connection with this incident and is in police custody.
Police are seeking to identify two further people who are believed to have been occupants in one of the vehicles.
Road closures are in place in Church Square, Hampden Gardens, Churchill Avenue, Carrington Road, and Chaloner Road. A scene watch also remains in place while officers carry out enquiries and examine the scene.
I understand that members of the public would be concerned about this incident, but I would like to reassure people that we believe these incidents to be linked and there is no threat to the wider public. There will be an increase in police presence in the area while this investigation takes place. If you have any questions or concerns, please feel free to speak to officers.