A 34-year-old man was stabbed to death and another injured during a clash at Sylvester Road in Ratmalana, Mount Lavinia, the police said.
They said it was a result of a clash on Monday between two groups.
The man, who was injured, was admitted to the Colombo South Teaching Hospital. The man who was killed was found to be a resident of Ratmalana.
No suspects have been arrested so far while Mount Lavinia police are conducting investigations.