According to microbloggers the loud speaking resulted in to the fight  

While it is not clear yet as to when the incident happened and inside which train, a video of the man’s angry act went viral on social media and was widely condemned.

After the video went viral, Chennai Central railway Police station registered a case under Sections 153 A (promoting enmity between different groups), 323 (voluntarily causing hurt), 294 b (uttering obscene words in public place) and have launched a search for the suspect.

Government Railway Police have registered a case and have launched a search for a man who verbally abused and assaulted Hindi speaking worker inside a train in Tamil Nadu.

In the truncated video The man, who appeared to be in an angry state was hurling verbal abuses at Hindi speaking workers in a train compartment and also at BJP political leaders.

What has transcribed before the fight unknown 

GRP also released a photograph of the suspect on social media and announced rewards for those providing information, leading to his apprehension. It is not known weather police send look out notice for the loud speaker in public forum

Police have also issued summons to the YouTuber who flagged the incident in twitter to cooperate with the police investigation.