A teenage stowaway was likely hitching a ride on a Queensland freight train when he fell and critically injured himself, police say.
The 18-year-old initially came to the attention of rail staff when he was spotted moving between carriages.
A search of the train failed to locate the teen, so staff began to scour the rail line.
He was found lying beside the tracks at Sellheim, southwest of Townsville at about 3pm on Monday.
Acting Senior Sergant Dean Cavanagh said they believed the teen, who was from nearby Charters Towers, was using the train for free travel.
"It looks like he was utilising it for transport as opposed to skylarking on there," he said on Tuesday.
The man was airlifted to Townsville Hospital in a critical condition with severe leg injuries.
Investigations are continuing.