Three persons were killed during an attack on an employee of the Lal Bahadur Shastri IAS Academy in Mussoorie in Uttaranchal in the early hours of Friday.
Four persons with country-made guns barged into the house of Kartar Singh, a security guard at the prestigious academy, at around 0615 IST and gunned down Vicky and Alka while they were asleep.
Later, they shot dead Kartar Singh before escaping on motorcycles.
Vicky and Alka had gone through a court marriage about eight months ago and since then had been living with Kartar and his wife Somwati Devi in the IAS academy campus.
Alka's family, which is from an upper caste, apparently did not accept the marriage.
One of the four assailants, Surinder Singh, was arrested following a manhunt, DIG (Crime) Anil Raturi told PTI.
On being interrogated, Surinder said the murder was committed at the behest of Alka's father Kunwar Singh, who was not happy with the marriage that took place against his wishes.
Later, police arrested Kunwar Singh from his house at Rajpur area in state capital Dehradun. Two country-made rifles allegedly used in the crime have also been recovered, Raturi said.
Police were searching for the other assailants, he said.
Director General of Police Prem Dutt Raturi told rediff.com that all the students and academic staff was safe.
The local police has registered a case of murder at the instance of Kartar Singh's wife Somwati Devi.
With inputs from PTI