This was the moment a group of students dangerously travelling on top of a moving bus fell onto the road as the driver slammed the brakes in southern India. <br /><br />The students were celebrating ‘Bus Day’ when the incident happened on July 17 in Chennai, Tamil Nadu state.<br /><br />Footage shows the party-goers falling off the roof of a bus after the driver stopped the vehicle.<br /><br />At least 20 students have been arrested by Chennai Police following the accident.<br /><br />Every year students in Chennai celebrate ‘Bus Day’, an event in which students party in buses that ferry them to and from universities.