A differently abled man hacked his sister and two nieces to death in West Bengal's South Dinajpur district, police said on Sunday.
The incident occurred at Chaynabas village on Saturday, an officer of Gangarampur police station said.
The accused lived with his sister, two nieces, and his sick father, he said.
On Friday, due to his deteriorating mental health condition, the family members of 28-year-old Babu Hossain had shackled him in chains, the officer said.
"However, as soon as the family members removed the shackles on Saturday evening, the accused got hold of a hoe lying in the house and killed his 30-year-old sister Mehernigar Khatun and nieces 22-year-old Gulnihar Parveen and 9-year-old Priyanka Khatun," he said.
The accused has been arrested and is being interrogated, he said, adding that the bodies have been sent for an autopsy.