The suspects were arrested close to dawn in Riyadh's al-Dilam neighborhood after crashing their getaway car, the official al-Ekhbariya news channel reported.
No official statement has been released regarding the motivation of the attack.
"However, some Saudi news outlets reported that the brutal attack took place after the parents regularly criticised ISIS and described the group as a terrorist organisation."
Meanwhile, Saudi social media users argued that the twins believed their parents were apostates for opposing Islamic State (ISIS, ISIL, IS and Daesh), The New Arab reports.
They shared details of the gruesome incident and expressed their horror that the suspects could commit such violence against their parents, especially during the holy month of Ramadan.
In September, two ISIS sympathizers lured their cousin - a member of the Saudi armed forces - to the desert and shot him dead on the first day of Eid al-Adha, while recording the entire incident.
Security forces aided by aircraft tracked the brothers to a mountainous area.
When asked to surrender, the two men opened fire. Eighteen-year-old Abdul-Aziz Radi Ayash al-Anzi was killed in the ensuing gunfight, and his brother, 21-year-old Saad Radi Ayash al-Anzi was wounded and arrested.
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