Three teenagers photographed train surfing in Melbourne's south-east have been labelled "stupid" by authorities who warn they are dicing with death.
The trio was caught by a keen-eyed commuter as they clung to the back of a Cranbourne-bound train at Hughesdale station last night, just after 7pm.
Inspector Philip Green from the transit safety division said the incident was being investigated after seeing the photograph taken by an Age reader.
Advertisement: Story continues below He said the teenagers were "coupling riding", which was "known for its self-evident mind-numbing stupidity".
"Every time it occurs, basically it's a death in waiting," Inspector Green said.
The passenger, who did not want to be named, said the boys were aged about 13 or 14 and had screamed abuse at him as they realised he was taking a photograph.
"Do their parents know what they're doing or what?" he asked.
He said about 20 minutes later two more teens, carrying beers, had jumped on the back of a city-bound train at the station.
Inspector Green said train surfers often rode the carriages to etch graffiti into train windows and were usually young males.
He said people had died train surfing and offenders often did not consider the impact on their family, friends and the wider community.
Metro Trains spokesman Chris Whitefield said train surfers could be fined up to $293 and face criminal charges.
"This sort of idiotic behaviour risks the safety of the people involved, and risks disrupting the travel of thousands of passengers if and when they fall off and get injured, or worse, killed," he said.
Metro is also investigating last night's incident. Mr Whitefield said people who witnessed train surfing could contact Metro on 1800 696 387.