It is understood the driver and passengers are from Northern Ireland.
One suspect was struck by at least one bullet and was treated for an injury to his upper body.
Police investigating Russian whistleblower Alexander Perepilichnyy's death kept bosses in the dark, confidential police papers reveal
'We asked them to investigate his death as a potential murder and asked them to as quickly as possible secure the evidence and look for toxicology tests, based on the murder by poison of Alexander Litvinenko. The police didn't respond.