Quoting eyewitnesses, police said Faryad attacked his sister-in-law and her three children - Azim (5), Wasim (3) and Shakil (2) - with a knife, cutting the throats of the children before severely injuring their mother.
The neighbours managed to overpower him while he was fleeing and handed him over to police.
The injured woman was shifted to hospital where her condition was stated to be critical. The children's bodies were moved to mortuary for autopsy.
Majid, the father of the slain children, told police that he left the house in the morning for work and his brother was waiting for the moment to kill his children and wife.
Faryad told police that he had killed Majid's children because he and his wife often taunted him and his wife for being issue-less.
A murder case has been registered against the accused.
