Mr Ravalmal, a businessman and social worker, was one of the main trustees of Parshwanath Jain Tirth.
"A pistol used in the killings was recovered from near the crime scene," the police officer said.
Someone known to them might have killed them as no evidence of forced entry into the house was seen, Mr Kabra said.
Their son and some other people who were in the house when the crime happened were being interrogated, Mr Kabra said, adding a murder case has been filed and the bodies have been sent for post-mortem.
Chief Minister Raman Singh expressed grief over the deaths. In his condolence message, the chief minister said Mr Jain played an exemplary role with utmost dedication in promoting yoga and naturopathy in Chhattisgarh.
He had also played an important role in setting up a naturopathy college in Nagpura, Mr Singh added.