RIYADH • Saudi Arabia's Crown Prince and Interior Minister sought to reassure Saudis of the kingdom's security after Monday's triple suicide attacks, which have sparked outrage.
At least four people were killed in the attacks targeting the holy city of Medina, the United States consulate in Jeddah, and Shi'ites in the city of Qatif.
No group has claimed responsibility, but the Islamic State in Iraq and Syria (ISIS) has carried out similar bombings targeting Shi'ite Muslims and Saudi security forces.
"The security of the homeland is good. It is at its highest levels and, thanks be to God, it gets stronger every day," Saudi Crown Prince Mohammed bin Nayef was quoted by the Saudi Press Agency as saying when he visited three people wounded in Jeddah.
The attacks have rattled Saudis who celebrate Eid al-Fitr today, following the month-long Ramadan.
Militant attacks on Medina, the second-holiest site in Islam after Mecca, are unprecedented.
The suicide bombing in Medina came during sunset prayers at the Prophet's Mosque, where Prophet Muhammad is buried and which attracts millions of pilgrims each year.
The Saudi Interior Ministry said in a statement that security forces became suspicious of a man who was heading for the Prophet's Mosque through a carpark.
"As they tried to stop him, he blew himself up with an explosive belt, causing his death and the death of four security personnel," the statement said, adding that five others were injured.
At the same time as the Medina attack, across the country in the Shi'ite-populated Gulf city of Qatif, another suicide bombing took place near a Shi'ite mosque. The Interior Ministry said "the body parts of three people were found" at the site but had not yet been identified.
The first attack took place in the western city of Jeddah, where two security officers were injured when a suicide bomber blew himself up near the US consulate in the early hours. No consulate employee was hurt in the attack, which coincided with the US July 4 Independence Day holiday.
The Saudi Interior Ministry identified the bomber as Pakistani resident Abdullah Qalzar Khan, 35, a private driver who had been living with his family in Jeddah for 12 years.
Cairo-based Al-Azhar, the highest authority in Sunni Islam, condemned the attacks and stressed "the sanctity of the houses of God, especially the Prophet's Mosque".
Saudi Arabia's supreme council of clerics said the attacks "prove that those renegades... have violated everything that is sacred".
Iran, the main Shi'ite power, also condemned the bombings and called for Muslim unity against extremists. "There are no more red lines left for terrorists to cross. Sunnis, Shi'ites will both remain victims unless we stand united as one," Iranian Foreign Minister Mohammad Javad Zarif said on Twitter.
In neighbouring Kuwait, officials arrested four people suspected of ISIS links for plotting attacks.
REUTERS, AGENCE FRANCE-PRESSE, NEW YORK TIMES