AHMEDABAD: Unhappy over their daughter's love marriage, a couple and their two sons allegedly consumed poison following which the man and one of his sons died in Gujarat's Ahmedabad district, police said on Wednesday.

The family members decided to take the extreme step as they were not happy with the woman's decision to marry a man of her choice about a year back, an official from Dholka police station said, adding both the families belong to the Dalit community.

Kiran Rathod (52), his wife Neetaben (50) and their two sons Harsh (24) and Harshil (19) from Dholka town here allegedly consumed a poisonous substance on Tuesday night in a bid to kill themselves, he said.

The man and his elder son died, while his wife and younger son survived and were undergoing treatment, he said.

"When the neighbours got to know about the incident, they called an ambulance and informed police. Doctors at a private hospital declared the man and his elder son brought dead, while the woman and the younger son are undergoing treatment," the official said.

The police have registered an FIR against 18 persons, including the husband of Rathod's daughter, her in-laws, other relatives and friends under Indian Penal Code Sections 306 (abetment of suicide), 506 (2) (criminal intimidation), and 114 (abettor present when crime committed).

Unhappy over the marriage, Rathod and his family severed ties with his daughter and refused to visit her at the place of her in-laws, as per the FIR.

In an attempt to resolve the issue, their daughter's in-laws and other accused persons caused them mental torture which they were unable to bear and decided to kill themselves, the FIR claimed.