A passenger is dead and his driver remains under police guard in hospital after their car crashed into a tree in Melbourne's south-east on Thursday afternoon.

Investigators believe three men were travelling in a sedan along Broadway, in Elwood, when the driver lost control about 4.15pm.

Broadway, in Elwood Credit:Gary Medlicott

One of the passengers, who is yet to be identified, died at the scene. The other male passenger was taken to hospital with serious injuries.

The driver was also taken to hospital and was under police guard on Thursday night.