Police were called to a report of a concern for a man's safety in Back Chapel Street, Bradford, at about 8.44am.
An air ambulance also landed nearby in response to the incident.
Officers attended and found a man aged in his 20s with serious injuries.
Emergency services treated the man at the scene, but he was sadly pronounced dead a short time later.
Police said early investigations suggest the man had fallen from height and the force is appealing for witnesses.
A spokesman for West Yorkshire Police said: "Early enquiries suggest the deceased has fallen from height.
"Bradford District CID is continuing enquiries at the scene to establish the circumstances of this incident.
"Anyone with information which may assist is asked to call 101, quoting log *0466 of today, or use the live chat facility on the West Yorkshire Police website. "