Monday’s first bombing, near the US consulate in Jeddah, was carried out by a Pakistani resident, Saudi Arabia interior ministry reported.
The suspect was later identified by the interior ministry as Abdullah Qalzar Khan, a 35-year-old private driver who had been living with his wife and her parents in Jeddah for 12 years.
Interior ministry spokesperson General Mansour al-Turki had told state Al-Ekhbaria news channel that the bomber was closer to a mosque in the area than to the consulate.
At least four people died in suicide bombings in Saudi Arabia on Monday following attacks elsewhere in the region before the end of the Muslim holy month of Ramazan.
There were no immediate claims of responsibility for the three attacks one of which, at the Prophet’s (PBUH) Mosque in Medina, left four members of the security forces dead and others wounded.
Since late 2014 Saudi Arabia has been hit by bombings and shootings claimed by the Islamic State group but multiple attacks on the same day are unusual.
The Prophet’s (PBUH) Mosque, in the west of the kingdom, is one of Islam’s holiest sites — where Muhammad is buried and which attracts millions of visitors each year.
“Security forces suspected a man who was heading towards Al-Masjid al-Nabawi as he passed through a visitors’ parking lot,” the interior ministry said in a statement.
“As they tried to stop him, he blew himself up with an explosive belt causing his death, and the death of four security personnel,” said the statement, adding that five others were injured.
The two other blasts occurred in the Red Sea city of Jeddah near the US consulate and in Shia-populated Qatif on the Gulf coast of the country.
The Al-Arabiya news channel showed images of fire raging in the parking lot with at least one body nearby.
Two security officers were wounded in the Jeddah bombing carried out by a Pakistani resident, the interior ministry said.
Residents of Qatif said body parts were found near a Shia mosque and the interior ministry confirmed the suicide bombing clarifying that “the body parts of three people were found” at that site but have not yet been identified.
The ministry said the deadly Medina attack occurred during sunset prayers after which Muslims break their Ramazan fast.
The Prophet’s Mosque is particularly crowded during Ramazan, which is supposed to be a time of charity but has seen spectacular attacks around the region.
Undeterred by the blast at the sprawling Medina mosque complex, thousands of worshippers performed prayers on Monday night, live Saudi television showed.
Sunni extremists from IS claimed or were blamed for, a suicide bombing in the Iraqi capital Baghdad on Sunday that killed more than 200 people as well as attacks in Bangladesh Friday night and at Istanbul’s Ataturk airport last week.
Monday’s bombings in Medina and Qatif took place simultaneously.
“Suicide bomber for sure. I can see the body” torn apart, said one witness to the attack in Qatif.
Another witness, who gave his name only as Ayman, told foreign media there were two explosions near the Shia mosque.
Pictures said to be from the scene and circulated by residents showed a small fire burning in the street, severed limbs and what appeared to be a head.
The ministry said in the statement published by the official SPA news agency that the bomber’s explosive belt had “partially” exploded.
The US embassy in Riyadh reported no injuries among the consulate staff.
A picture carried by the Sabq online newspaper, which is close to authorities, showed a large body part lying on the ground between a taxi and the open door of another car that was peppered with holes.
The attack coincided with the US July 4 Independence Day holiday.
Since late 2014 a series of bombings and shootings claimed by IS in Saudi Arabia has targeted minority Shias as well as members of the security forces, killing dozens of people.
Most of the attacks have been staged in Eastern Province, home to a majority Shias in the Sunni-dominated Gulf state.
Millions of expatriates, many from Muslim-majority nations in the Middle East and Asia, work in the kingdom.
IS leader Abu Bakr al-Baghdadi has called for attacks on Saudi Arabia, which is taking part in the US-led coalition bombing the militants in Syria and Iraq.
The group also considers Shias to be heretics.