The boy was hit by a fallen tree in Blackburn South about 6pm and was taken to the Royal Children's Hospital in a critical condition.

He later died in hospital.

The other two people were killed in separate incidents.

A 36-year-old woman also died after a tree hit the ute she was a passenger in along the Maroondah Highway in Fernshaw around 7pm.

It is believed a utility was travelling along the Maroondah Highway when it was struck by a falling tree.

The 24-year-old male driver was taken to hospital with minor injuries.

In another incident, a 59-year-old man died after a tree fell on his car as he was leaving a shopping centre in Belgrave.

Police are preparing coroner's reports for all three incidents.

Emergency services received more than 1000 calls for help during the wild storms, after a severe weather warning forecast wind gusts of up to 158 kilometres per hour.

Australian Associated Press