Police are investigating a series of robberies, assaults, an armed robbery and a criminal damage which occurred in Sunshine overnight.
Officers have been told a 35-year-old Braybrook man was walking along Hertford Street about 11.25pm when he was set upon by a group of 10-15 males.
His pockets were searched and demands made for his wallet before the group were scared off by local residents.
He was taken to hospital suffering minor injuries.
Investigators believe the same group entered Kennedy Street and assaulted a 16-year-old Sunshine boy.
His friend, a 15-year-old Melton boy, came to his aid but was also assaulted and had his keys and mobile phone stolen.
Both boys were taken to hospital with the 16-year-old suffering critical injuries and the 15-year-old suffering serious injuries.
A 13-year-old Melton boy and a 13-year-old Melton girl were also accosted by the group as they entered Kennedy Street.
The 13-year-old boy was then assaulted by the group and suffered minor injuries.
The group then attended the intersection of Kennedy Street and Devonshire Road where they used a stick to assault a 14-year-old Corio girl.
She was searched and her mobile phone stolen.
Police believe the group then damaged a nearby car by throwing a rock through the rear passenger window.
The offenders are perceived to be African in appearance, male and aged between 14-20 years of age.
Anyone who witnessed the incidents or with information is urged to contact Crime Stoppers on 1800 333 000 or make a confidential on-line report at www.crimestoppers.com.au