Police responding to reports of a burglary found the body of a 17-year-old boy.
Bedfordshire Police were called to reports of suspicious activity at an address in Linslade, Leighton Buzzard, at around 10.25pm on Thursday.
The teenage boy was found unresponsive and received first aid, but was pronounced dead shortly afterwards, the force said.
A man was arrested at the scene on Soulbury Road on suspicion of murder, while three other men were detained in connection with the incident. They have since been released on bail.
Detective Inspector Caeva Taylor said that although the initial 999 call was to report a possible break-in, police had so far found "no evidence whatsoever that the victim was carrying out, or attempting to carry out, a burglary".
The boy's next of kin have been informed and are being supported by specially trained officers, police said.
Earlier, Ms Taylor said: "This is an incredibly tragic incident in which a 17-year-old boy has lost his life and our thoughts are with his loved ones at this unimaginably difficult time."
She added: "Our team is working hard to establish what has led to the boy's death and we understand the concern this will cause in the community."
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Officers have asked anyone with information to get in touch via the non-emergency number, 101, quoting reference Operation Breakwater, or to contact Crimestoppers anonymously.
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