A 20-year-old man was stabbed in Dudley High Street in the early hours of Sunday morning and was left in a "critical condition".
Two men aged 25, a 22-year-old and an 18-year-old, were arrested in Northamptonshire on suspicion of grievous bodily harm.
A spokesman for West Midlands Police said the four had been released on bail while enquiries continued as they appealed for help.
They added: "We would encourage anyone with CCTV, mobile phone or dash-cam footage to get in touch via Live Chat on our website, quoting log 518 of January 29."
