The video of the incident went viral on social media.

A group of college students sitting on the roof of a city bus in Chennai fell on to the road when the driver applied the brakes suddenly to avoid hitting a two-wheeler.

The video of the incident on Monday went viral on social media.

The students of Pachaiappa's College in Chennai climbed atop the bus to celebrate 'Bus Day'.

Police took some students into custody.

#WATCH College students in Chennai sit & climb on top of moving buses and hang from window bars of a bus during Bus Day celebrations, yesterday; Police detained 24 students in connection with the incident. pic.twitter.com/TI77ogTNxc — ANI (@ANI) 18 June 2019

'Bus Day' is celebrated as a thanksgiving to the driver and the conductor who are regulars on a particular college route.

Over time, the celebrations have turned into a nuisance for the public with students forcing the driver to drive the vehicle very slowly, thereby blocking the traffic on busy roads.

The Madras High Court has come down heavily on Bus Day celebrations several times. The police too had issued warnings against the celebrations.