Three students died and four more were injured when they were hit by a signalling post while travelling on the footboard of a Chennai electric train on Thursday morning, officials said.
The incident occurred at 9.15am near St Thomas Mount railway station.
The three students who died fell after one of their bags got entangled in the signalling post, a Railway Police Force (RPF) officer said. The other four fell after losing their balance.
While two died on the spot, the third died of his injuries while being taken to the Chromepet Government Hospital.
The injured are currently undergoing treatment in the same hospital. Police are yet to identify them, or where they were studying.