Two teenage boys were assaulted and robbed in Kookaburra Avenue, Werribee earlier this month.
Detectives from the Altona North Divisional Response Unit are investigating the incidents, which occurred on November 9.
Police said that a 13 year-old Hoppers Crossing boy was walking around the avenue at around 4.30pm, when a group of males – who are all perceived to be African in appearance – approached him.
One of the males reached into the victim’s pocket and stole his mobile phone. The victim attempted to grab the phone back and he was assaulted.
A 16 year-old Hoppers Crossing teenager, who who was riding past at the time, was also assaulted before his bike, watch and phone were stolen.
The offenders fled the scene on foot.
The two victims sustained non-life threatening injuries and received medical treatment.
The investigation remains ongoing and police are appealing for anyone who witnessed the incident or with any information to contact Crime Stoppers on 1800 333 000.