The bodies of a 21-year-old man and a 20-year-old woman riddled with bullets were found inside a house in Uttar Pradesh's Noida on Monday, police said.
The police said the married woman and the unmarried man were in a relationship for the past six months but it was unclear whether they both killed themselves or were shot by one of them.
Both the dead worked as daily wage earners, a senior officer said.
The incident took place around 3 pm at a house in Ambedkar Colony in Sector 123, under Phase 3 police station limits, Deputy Commissioner of Police, Central Noida, Harish Chander said.
"They both lived in neighbouring houses and have been in an affair. However, the woman was married and that is why they could not get together. This apparently led to the incident. The firearm has been recovered from the spot," Mr Chander said.
The bodies have been sent for a post-mortem after which it would be confirmed if it is a case of double suicide, the police said, adding no complaint has been made by anyone in the matter so far.