A second blast ensued on Monday near a mosque in the Shia city of Qatif in the Eastern side of the country, Xinhua cited Al Arabiya local news as saying.
No further details were officially reported regarding the blast that occurred shortly after a twin blast near a mosque in Qatif.
The two incidents occurred hours after a suicide bomber blew himself up in a hospital's parking lot in Jeddah to avoid being arrested by police.
The blast struck at sunset while residents of the area broke their fast the day before the final day of the holy month of Ramadan.
Al Arabiya highlighted that no injuries were reported among worshipers who were praying in the mosque.
Several bombs were defused in the blast location.