Two people have been arrested on suspicion of murder after the death of a 16-year-old boy found with stab wounds.
Police were called to Friars Wharf, Oxford, at 7.55pm on Wednesday but despite the best efforts of paramedics he later died in hospital.
A Thames Valley Police spokesman said a 25-year-old woman and a 33-year-old man, both from Oxford, were arrested on suspicion of murder and remain in custody for questioning.
The next-of-kin of the victim, who is from the Birmingham area, have been informed, the spokesman said.
He added: "Officers remain in the area, and a scene watch has been put in place while an investigation is carried out."
Detective Chief Inspector Andy Howard said: "We are in the early stages of this investigation but we have already made two arrests.
"I understand that this incident will cause concern in the community, but I would like to reassure people that we are carrying out a full and thorough investigation.
"Members of the public can expect to see an increased police presence in the area in the coming days while our officers make inquiries.
"We would like to hear from anyone who witnessed this incident, or who has any information which could relate to it, no matter how insignificant it may seem.
"If you have any details which you think could help our investigation, please call the Thames Valley Police non-emergency number on 101."