you may issue them first show cause notice letter (Chargsheet), let them revert on the same, if you are succeed to take the guilty letter from them, so, you may issue him warning letter or termination, if u still want to give them a chance.. but, seriouse action from HR shall be keep good example for rest of employees.
Its really a bad concern..The worst point is that other employees had to suffer from bad language between two persons fight.This is non tolerable in any organization.
You should do one thing call an urgent meeting with seniors and both persons and ask the genuine reason of this fight and after discussing with them if it seems that they are feeling themselves guilty and want to rectify their mistake.Ask them to write an apology letter and paste it on notice board But if they seem with same approach and not feeling guilty then terminate them.
Also have a meeting with all employees and strictly convey them that this was the last mistake and show of indiscipline and another mistake by anyone in organization will lead to some serious action against the particular employee.If possible issue a corrective action policy in your organization mentioning all rules and penalities.This will help you in further.
Good Luck !!!
* Please issue the showcase notice to them and ask them to provide Written answer in 72 hours.
* After showcase notice inquire the matter and let them give their opinion on this matter.
* If company is using CCTV camera than record the same for proof.
* After three days based on all proof and written explanation from them issue Warning letter / Termination letter / Suspension letter.
* Keep all the documents of disciplinary procedure in to their employee file and Online system if your company is using.
* Cut the marks in PMS for their Behavioral section.