The man felt humiliated and plotted a revenge to kill the Ahujas.
A couple and their domestic help were murdered at their three-storey home in Delhi on Tuesday by two sacked employees in what police say was an "act of revenge".
The killers missed the couple's two-year-old sleeping daughter as she was under a blanket, officials said.
Shalu Ahuja, who ran a beauty parlour on the ground floor of the building in Ashok Nagar in east Delhi, had sacked two of her employees a few days ago. She had accused the two of "unprofessional behavior" when she learnt they were in a relationship. Her husband Sameer Ahuja also had an argument with them.
The man felt humiliated and plotted revenge to kill the Ahujas, according to the police.
He discussed his plan with his girlfriend and two more friends - Sachin and Sujit - who agreed to help him. They roped in two more men, police said.
Security footage reveals that five people arrived in two bikes at around 8 am and entered the house.
The bodies of Shalu Ahuja and her domestic help, Sapna, were found on the ground floor. Sameer Ahuja was found dead on the first floor of the building with injuries to his face and head.
"They did not kill the child because they could not find her," an official said.
The throats of the two women were slit. Sameer Ahuja's head was bashed in with a frying pan, officials said.
The help, Sapna, was killed because she happened to be present at the time, the police said.
Sameer and Sujit have been arrested. Four others, including the two main accused, are missing.