A suicide bomber blew himself up near a security office of the main mosque of Al-Masjid an-Nabawi in Medina, reports said.
Two security officers have been killed in the blast which occurred in the parking area. Four people have been seriously injured.
Known as the Prophet’s Mosque, Al-Masjid an-Nabawi is the second holiest site in Islam, after Mecca and is visited by millions every year.
Video footage circulating on social media showed a vehicle which had caught fire and huge plumes of smoke billowing from the area adjacent to the mosque.
No one has claimed responsibility for the bombing.
The suicide bombing in Medina followed two explosions in the eastern city of Qatif on Monday evening.
The first blast which took place near a mosque destroyed a car, a Reuters report said.
The second explosion occurred just before at 7 pm local time.
— Michael Horowitz (@michaelh992) July 4, 2016
Qatif in eastern Saudi Arabia is home to most of the minority Shia community. The target of the bomber seem to have been the Shia mosque.
There are no reports of any casualty so far.
A witness said body parts were strewn all across.
This video shows more clearly the site of the #Medina attack. Source: https://t.co/gQkeyLauLK pic.twitter.com/IefNSS0Y9v
— Ragıp Soylu (@ragipsoylu) July 4, 2016
— Press TV (@PressTV) July 4, 2016
Another witness told AFP that he had seen a suicide bomber blow himself up near the Qatif mosque.
The explosions comes hours after a suicide bomber blew himself up near the US consulate in the port city of Jeddah. The blast injured two security officers.
The explosions in Saudi Arabia comes two days before the oil rich kingdom is set to celebrate Eid-ul-Fitr on Wednesday, after fasting in the holy month of Ramadan.