A man is believed to be in a critical condition after a stabbing at Perronet House in Princess Street.
Police were called just before 3 o'clock on Friday morning to reports of a stabbing at Princess Street at the Elephant & Castle.
A man, believed to be in his 30s, was taken to hospital with stab wounds. His condition is thought to be critical.
A Southwark Police spokeswoman confirmed that one man has been arrested in connection with the incident.
He is in custody at a south London police station.