Robbers decamped with cash and valuables after assaulting Kurukshetra university employee Vivek Ratan and his family last night, they said.
Ratan, his wife, brother and his wife, suffered serious injuries in the incident, police said.
A gang of six persons armed with axes, swords and iron roads barged inside Ratan's house, they said, adding the robbers killed the elderly couple and attacked the other family members when they tried to resist the loot attempt.
The matter is being probed, police said.
Office bearers of Kurukshetra University Non-Teaching Employees Association condemned the double murder and demanded immediate action in the case.