Police were called to John Street, in Bradford city centre, shortly after 5.45am on Sunday, Oct 10.
Two 19-year-old men were found with stab wounds.
West Yorkshire Police confirmed that one of the men died a short time later.
The other man is in hospital in a critical but stable condition.
A youth aged 16 and a 26-year-old man were arrested on suspicion of murder and attempted murder and are currently in custody.
Today, West Yorkshire Police confirmed that they have now arrested a third man on suspicion of murder.
The 21-year-old man from Bradford remains in custody.
The Homicide and Major Enquiry Team are continuing to investigate the incident and would like to hear from anyone with any mobile phone, CCTV or dash cam footage which may assist detectives with their enquiries.
The team can be contacted by calling 101, or using the 101 Live Chat facility on the West Yorkshire Police website, quoting crime reference 13210516983.
Information can also be passed to independent charity Crimestoppers anonymously on 0800 555 111.