A woman is in custody after a man died following an incident in Mirrabooka on Wednesday morning.

Police were called to a home in Tinsel Place Mirrabooka about 8.40am, where they found a man with life-threatening injuries.

A St John Ambulance spokesman said the man had "traumatic injuries" to his upper body and was taken to Royal Perth Hospital as a priority one patient, but died a short time later.

The circumstances surrounding the man's injuries are not yet known. Police have since confirmed a woman is in custody and is assisting Homicide Squad detectives with their investigation.

More to come.