Four soldiers killed at Bathinda military station are not from 18 horse regiment.

Claim
Sources within the #IndianArmy have reported that a Sikh soldier allegedly killed four Hindu soldiers belonging to the 18 Horse Regiment at the Bathinda Military Cantonment.
Rating
Explanation
A recent firing incident in Bathinda military station has left four Army jawans killed. In this situation, it is claimed that a Sikh soldier killed four Hindu soldiers belonging to the 18 Horse Regiment at the Bathinda Military Cantonment. Some of the posts with such a claim can be seen here and here.
What is the truth?
When searching with relevant keywords, a Reuters article is found reporting that two unknowns were involved in the attack and that it has no terror angle. Four soldiers succumbed to gunshot injuries sustained during the firing incident.
The India Today article mentions that the four soldiers who died were from Indian Army’s 80 Medium Regiment – an artillery unit. Two unidentified people in civilian clothes are believed to be behind the incident. “It is not a terrorist attack, it is not an attack from outside. It is a fratricidal incident”, told Punjab police.
The Wire article mentions that the two men were wearing kurta-pyjamas with their heads and faces covered, and fled from the spot. And the four jawans (two from Tamil Nadu and two from Karnataka) are identified as Sagar Banne, Yogesh Kumar J, Santosh M, Nagaral and Kamalesh R.
The 18-horse regiment is not a part of the Indian Army. The Indian Army website shows 1 Horse, 4 Horse, 9 Horse, 14 Horse and other regiments but not 18 Horse regiment. Moreover, 18 horse regiment exists in Pakistan army.
Conclusion
It is found that 18 horse regiment is not a part of the Indian army and four jawans killed were from the 80 medium regiment. And the men involved in the attack are yet to be identified.