Saudi officials have arrested 19 people after three bomb attacks took place on Monday in Qatif, Jeddah and the Muslim holy city of Medina.
An interior ministry spokesman said that 12 of the 19 people arrested for the attacks are Pakistani nationals. The suicide bomber who killed four security officers near the Prophet's Mosque in Medina was named as 26-year-old Saudi national Naer Muslim Hamad.
Hamad killed four soldiers in a parking lot near the mosque in Medina after detonating an explosive belt, the Saudi Press Agency quoted an interior ministry spokesman as saying.
The ministry also said that three people who were arrested in connection with the attacks in Qatif were Saudi nationals Abdulrahman al-Omar (23), Ibrahim al-Omar (20) and Abdulkarim al-Husni (20). Authorities added that none of the suspects had obtained national IDs.
As of yet, no group has claimed responsibility fo the attacks, however it is suspected that those arrested may be connected to the Islamic State group.
The IS group have carried out previous attacks in the kingdom, often targeting Shia-majority areas.
IS and other Sunni extremists consider Shias to be apostates deserving of death, carried out a suicide bombing on a Shia mosque in Qatif in May 2015 that killed 21 people.