Medina bombing: Saudi Arabia arrest 12 Pakistanis
Saudi officials say 12 out of 19 people arrested over Monday's three bomb attacks in the country are Pakistani.
An interior ministry spokesman also named a suicide bomber who killed four security officers near a mosque in the sacred city of Medina as Naer Muslim Hamad, a 26-year-old Saudi man.
The ministry said he had a history of drug abuse.
Three people who allegedly carried out attacks in Qatif were also named and identified as Saudi nationals.
Their names were given as Abdulrahman al-Omar (23), Ibrahim al-Omar (20) and Abdulkarim al-Husni (20). The ministry said none of them had Saudi IDs.
The attacks in Qatif took place on the same day and were also suicide bombings.
A man died in Jeddah on Monday when attempting to detonate a bomb.
No group has claimed responsibility for the attacks yet but they are suspected to have been the work of people with allegiances to so-called Islamic State.
The group has previously targeted Saudi security personnel and Shia mosques.
Monday's attacks happened at the end of the holy month of Ramadan, in which an IS spokesman had called for "a month of calamity for unbelievers".
During this year's Ramadan, there have been multiple attacks carried out by IS sympathisers across the world.