Tasman Police say the man who died in Nelson yesterday knew the person alleged to have shot him.
Police were called to a Washington Road property in Nelson shortly before 1.30pm.
Emergency services conducted CPR, but the 22-year-old man died at the scene.
Detective Inspector Mark Chenery says the two parties are known to each other and the police are satisfied there is minimal risk to the wider community.
Anyone who witnessed anything in the Washington Road area yesterday between 12.45pm and 1.30pm is asked to come forward.
The investigation team is also interested in hearing from people who have any CCTV footage of Washington Road, police say.