Police are trying to identify hundreds of passengers who pulled the emergency cord of a train and walked along the tracks after being told it would not be stopping at the next station.
Although initial reports suggested there were about 80 people on the tracks, British Transport Police now believe there could have been up to 200 people involved when the train stopped abruptly between Clifton Down and Redland Station in Bristol on Saturday.
The disgruntled passengers pulled the emergency stop cord after being told that the Great Western Railway service would not stop at Redland station on Saturday.
It is believed that many of those involved were students on their way to a music festival Tokyo World.
There are reports that the train was very overcrowded, but BTP said they were treating it as a "trespass incident".
BTP said they were called to the track in the Redland area of Bristol at about 3.30pm on Saturday following reports there were crowds of people walking on the line.
After students packed onto the carriages at Clifton Down station, it was announced that the train would not be stopping at the next station, Redland, due to overcrowding.
Epigram News reports that students on the overcrowded train began to panic and started chanting: "Let us off, let us off."
One student told Epigram: "It was awful, I was trapped in the corner. I’m claustrophobic so I started panicking and I felt like I couldn’t breathe. People around us were shouting to the guys nearest to the window to smash it open."
There were also reports that a person fainted after having a panic attack.
Officers from BTP were called to the scene and helped the group get off the line.
A spokesman for BTP said: “On arrival it was established that, as the train came to a stop shortly after leaving Clifton railway station, the emergency cord had been pulled and people had got off the train and started to walk back towards the station.
“BTP officers at the scene helped to get the group off the line and to a place of safety.
“We are treating this as a trespass incident – one which caused numerous delays to services in the area and could have put lives in danger – and inquiries are currently underway to identify those involved."
Train operators have condemned the actions of the passengers, saying they put their lives, and those of their fellow passengers in jeopardy.
A Great Western Railway spokesman said: “Railway lines are designed for trains, not people and are inherently dangerous places. The actions of this group of passengers, whatever their reasons, endangered not only themselves, but also their fellow passengers.”
A Network Rail spokesperson said: “These individuals put themselves and others at great risk, and inconvenienced hundreds of other people.
“The railway is a hazardous environment, which is why railway trespass is a criminal offence, carrying a maximum fine of £1,000. We will be assisting BTP in their enquiries.”