Witnesses Jason and Michelle, who did not want their surnames used, arrived at their car in the station carpark at 2.30pm when they watched a security guard approach three male youths attempting to walk through a restricted area. 

An altercation ensued and the witnesses said they saw the security guard, a V/Line employee, holding his nose and his orange fluoro coat was sprayed with blood.

"They guy told them they weren't able to pass," Michelle said. "Next thing three guys are beating the sh*t out of him," .

She said the youths, who did not appear to be over the age of 21, fled on foot towards Seymour's on Lydiard on Lydiard Street. 

She said one was wearing a fluoro tradie jumper with khaki cream shorts, another youth was wearing navy blue pants with white stripes and a navy jumper and another male was wearing a navy jumper with a navy backpack.

Anyone with information should contact Crimestoppers  1800 333 000