A Saudi official says one of two attackers who wore explosive belts in Friday’s deadly assault on a Shiite mosque in the country’s east was a 22-year-old national.

Saudi Interior Ministry spokesman Maj. Gen. Mansour al-Turki identified the attacker in a statement carried late Saturday by the official Saudi Press Agency as Abdulrahman bin Abdullah bin Suleiman al-Tuwaijri.

Al-Tuwaijri and another gunman targeted the Imam Reda Mosque in al-Ahsa during Friday prayers. Al-Turki says four Saudis were killed and 33 people were wounded in the attack.

Al-Tuwaijri detonated his payload during the assault and died. The second attacker is in custody and is being treated for wounds. He was not identified.

No group has claimed the attack, but Islamic State militants have targeted the kingdom’s minority Shiites in the past.