Police were alerted by London Ambulance Service at approximately 3.15am on Sunday, 2 August that two men had self-presented at a south London hospital with stab wounds.
A 34-year-old man is in hospital in a life-threatening condition.
The other man, 27-year-old, is not believed to have sustained life-threatening injuries.
The two men are believed to have sustained their injuries during a fight on High Holborn, a crime scene remains in place.
At approximately 3.30am that same day, officers stopped on Clerkenwell Road after seeing a car parked with its hazard lights on.
In the car were two 25 year-old-men with stab injuries. Officers provided first aid until LAS arrived and the two men were taken to hospital.
One man has since been discharged for hospital and has been arrested on suspicion of GBH and is currently in custody.
The other man remains in hospital in a life-threatening condition
The investigation is in its early stages, however these incidents are currently being treated as linked and originating from the fight on High Holborn