A man is in hospital after a vicious attack outside a busy Melbourne train station during peak hour.

Police are hunting for the offender, who assaulted the 21-year-old Melton man, in what police said was an unprovoked attack at a Footscray bus stop last Tuesday at 5.30pm.

Detective Sergeant Steve Hill from the Transit Crime Investigation Unit said the victim was beaten unconscious.

“It appears to be a completely random attack which is concerning, [because of] the seriousness of the violence,” he said.

“Unfortunately it seems like the victim just looked the wrong way, so this kind of street violence needs to be addressed.”

The victim, who sustained head injuries and loss of consciousness after hitting the pavement, remains at Western General Hospital.

Investigators are calling on a number of witnesses to come forward, including a woman who intervened, preventing the attack from becoming worse.

The offender is described as Southern European, approximately 178cm tall, with a thin build and brown hair.

Anyone with information is asked to contact Crime Stoppers on 1800 333 000.