Khalid and Saleh Al Areeni, 20, allegedly stabbed their mother, 67, father, 73, and their brother Sulaiman, 22, in their home in Riyadh, Saudi Arabia, before stealing a car and fleeing.
A spokesperson for the Saudi Arabian interior ministry said: "The security authorities received a call at 1:12 am on Friday about an utterly heinous crime committed by Khalid and Saleh Al Areeni.
"The twins stabbed their mother, 67, father, 73, and their brother Sulaiman, 22, in their home.
"Investigations revealed that they lured their mother to the storeroom and stabbed her several times.
"Then, they went to the father and treacherously stabbed him before chasing their brother and stabbing him as well.
"They used a cleaver and sharp knives they brought from outside. The mother died on the spot and the father and brother were critically injured and were taken to a hospital."
The twins were arrested in Delm, around 100 kilometres south west of Riyadh, reports Gulf News .
According to local reports, the mother had told the twins that she would report them to the authorities if they kept planning to leave the country and join the ranks of ISIS.
Saudi Arabia was stunned by the savagery of the crime, with many asking why the two young men, who appeared to come from a loving and caring home, could turn into killers.