Two teenagers are on the run following an "unprovoked" stabbing at a bus stop and a shopping centre attack.
The violence started when a 70-year-old man was assaulted at a pharmacy at Keysborough in Melbourne's southeast just before 5pm on Friday.
Two youths with suspected stolen items attempted to leave the shop when the man tried to intervene, according to police.
The Dandenong North man suffered serious injuries and was taken to hospital.
About two hours later, a 16-year-old boy was stabbed at a bus stop in Centre Dandenong Road in nearby Dingley Village.
The boy was again assaulted when he tried to get away and later taken to hospital with serious injuries.
Police say the two teens wanted over the pharmacy assault are believed also to have been responsible for the bus stop stabbing, describing it as "what appears to have been an unprovoked attack".
The wanted teens fled before officers arrived at the scene.
Investigators are urging anyone with information about either incident to come forward.