Suffolk Police have established a police cordon on Foundation Street in Ipswich town centre following reports of a serious assault.
Police were contacted by the East of England Ambulance Service at 10pm on Sunday 18 December, following reports of two seriously injured men on Foundation Street in Ipswich.
Both men have been taken to hospital in a critical condition, with what are being described as life threatening injuries.
Two people have been detained by police in connection with the incident and will be questioned by detectives.
Foundation Street will be closed between Wingfield Street and Smart Street, and Rosemary Lane and the NCP Blackfriars car park will also be closed, while investigations continue.
The closures are expected to remain in place at least for the duration of Monday morning (19 December).
Any witnesses or anyone with information about this incident is asked to contact Suffolk Police on 101 quoting CAD number 391 of Sunday 18 December, or alternatively contact Crimestoppers anonymously on 0800 555 111.