A TEENAGER has died in front of his younger brother after leaning out of a moving train in Melbourne’s southeast.

Police said the 17-year-old Beaumaris boy was on the Frankston-bound train with his brother and a girl about 9.20pm yesterday.

The Herald Sun understands the group entered the rear driver’s cabin and leaned out to film themselves while the train was moving.

The teen fell when he was struck by a signalling sign, 200m from Malvern station.

The train driver was unaware what had happened.

Acting Sergeant Andrew Kiss described it as a tragic accident that would affect his family and friends.

“It appears he may have been hanging on the side of the train or from the train when his head hit the signage,” he said.

He said the accessibility to the rear doors would now form part of the coroner’s investigation.

“All I can say is, ‘don’t do it’,” he said.

Ambulance Victoria spokesman Ray Rowe said paramedics treated the teenager on the rail line for upper body and leg injuries.

He was taken to The Alfred hospital in a critical condition but died shortly before 11pm.

No one else was injured.

Metro Trains spokeswoman Leah Waymark said trains were safe if people followed the rules and did not take risks.

“This is a case of a handful of youths taking one risk too many and sadly ending the life of a young man,” Ms Waymark said.

“The train network is not a playground for thrillseekers and we are doing more and more monitoring of CCTV to reduce this sort of risk-taking behaviour.”