Saudi authorities said Monday that an Egyptian man was the second assailant in the weekend suicide bombing at a Shiite mosque that killed four people and wounded 36 others.
The interior ministry identified the man who was overpowered by worshippers during Friday's attack as Talha Hisham Mohammed Abdo.
Witnesses had said he randomly shot at worshippers before he was disarmed.
The other attacker, who blew himself up at Al-Rida mosque in Eastern Province, was identified Sunday by authorities as Saudi national Abdulrahman Al-Tuwaijri.
No one has yet claimed responsibility for the attack, the latest in a series of assaults against members of the Shiite community in Sunni-ruled Saudi Arabia.
The Sunni extremist Islamic State group has claimed responsibility for previous bombings and shootings.