British Transport Police (BTP) said the incident happened around 5pm on Monday at Rutherglen station in South Lanarkshire.
BTP said a teenage boy suffered serious injuries to his chest and lower body and was taken to hospital in a critical condition.
Two boys aged 14 and 18 were arrested following the incident.
The 14-year-old, from Glasgow, has since been charged with attempted murder and is expected to appear at the city's sheriff court on Wednesday.
The 18-year-old has been released without charge.
ScotRail said services were prevented from stopping at the station while emergency services dealt with the incident, but later resumed.
BTP officers were at the scene today as investigations continue.