Two men have been arrested on suspicion of murder after an 18-year-old man died of "significant injuries".
Police were alerted by paramedics who were called to an address in Sackville Street, Portsmouth, Hampshire, where the "seriously injured" man was found at 2.18am on Saturday.
The teenager was taken to the Queen Alexandra Hospital in Portsmouth where he later died.
A Hampshire police spokesman said that a 28-year-old man and a 32-year-old man, both from Portsmouth, have been arrested on suspicion of murder and remain in custody.
Chief Inspector Marcus Cator said: "We understand the community will be concerned about the incident in the city overnight in which a young man lost his life.
"Detectives are working hard to establish the circumstances and have since made two arrests."
Police earlier said that officers were carrying out enquiries in other areas of the city after receiving information that the victim might have been assaulted earlier in the evening.