Explosion near one of Islam's holiest sites in Saudi Arabia

State-linked Saudi news websites reported an explosion Monday near one of Islam's holiest sites in the city of Medina, as two suicide bombers struck in different cities without killing anyone.

Sabq news site reported the explosion, and other sites showed images of what appeared to be a fire outside one of the buildings overlooking the Prophet's Mosque. It was not immediately clear if anyone was killed or wounded in the blast.

The sprawling mosque where the Prophet Muhammad is buried is visited by millions of Muslims from around the world each year during pilgrimages to Mecca. The area would have been packed with pilgrims for prayer during the final days of the Muslim holy month of Ramadan, which ends this week.

The Interior Ministry could not be immediately reached for comment.

Also Monday evening, a suicide bomber and a car bomb exploded near a Shiite mosque in eastern Saudi Arabia, according to a resident there, several hours after another suicide bomber carried out an attack near the U.S. Consulate in the western city of Jiddah.

The possibility of coordinated, multiple attacks across different cities in Saudi Arabia on the same day underscores the threat the kingdom faces from extremists who view the Western-allied Saudi monarchy as heretics and enemies of Islam. Saudi Arabia is part of the U.S.-led coalition fighting the Islamic State group in Iraq and Syria.

The attack in the eastern region of Qatif did not appear to cause any injuries, said resident Mohammed al-Nimr, whose brother is Nimr-al-Nimr, a prominent Saudi Shiite cleric executed in January. He told The Associated Press the bomber detonated his suicide vest when most residents of the neighborhood were at home breaking the daily Ramadan fast.

Qatif is heavily populated by Shiites, who are a minority in the Sunni-ruled kingdom. Al-Nimr said that near the body of a suicide bomber was a car bomb that also went off around the same time.

The IS group's local affiliates in the kingdom have previously attacked Shiite places of worship, including an attack on a Shiite mosque in Qatif in May 2015 that killed 21 people.

Earlier Monday, the Interior Ministry said a suicide bomber had detonated his explosives when security guards approached him near the U.S. Consulate in Jiddah. The attacker died and the two security men were lightly wounded, according to the ministry statement, which was published by the state-run Saudi Press Agency. Some cars in the parking lot were damaged.

Interior Ministry spokesman Maj. Gen. Mansour al-Turki was quoted in the statement as saying the guards noticed the man was acting suspiciously at an intersection on the corner of the heavily fortified consulate, near a hospital and a mosque.

The U.S. Embassy in Saudi Arabia confirmed there were no casualties among consular staff, and said it remains in contact with Saudi authorities as they investigate.

No one immediately claimed responsibility for the attack.

The Interior Ministry did not say whether the bomber intended to target the U.S. diplomatic compound, adding that an investigation is underway to determine his identity.

The state-run news channel al-Ekhbariya, quoting the Interior Ministry, said the bomber was not a Saudi citizen, but a resident of the kingdom. It gave no further details on his nationality. There are around 9 million foreigners living in Saudi Arabia, which has a total population of 30 million.

Footage aired on the channel after the attack showed crime scene investigators and police casing the area for evidence and dusting for fingerprints. Al-Ekhbariya said security forces detonated six explosive devices found at the scene.

A 2004 al-Qaida-linked militant attack on the U.S. Consulate in Jiddah killed five locally hired consular employees and four gunmen. The three-hour battle at the compound came amid a wave of al-Qaida attacks targeting Westerners and Saudi security posts.

More recently, Saudi Arabia has been a target of Islamic State attacks that have killed dozens of people. In June, the Interior Ministry reported 26 terror attacks in the kingdom in the last two years.

The U.S. Embassy regularly issues advisory messages for U.S. citizens in Saudi Arabia. In a message issued Sunday and another one issued after the attack Monday, the embassy urged Americans to "remain aware of their surroundings, and take extra precautions when travelling throughout the country." It also advised citizens to "carefully consider the risks of traveling to Saudi Arabia."

In neighboring Kuwait on Monday, security forces said they had arrested several suspects with alleged ties to IS, including an 18-year-old man who was planning to attack a Shiite mosque in the final days of Ramadan. Officials did not say when the arrests took place. An IS affiliate claimed responsibility for a suicide bombing carried out by a Saudi man last year in one of Kuwait's oldest Shiite mosques. That attack killed 27 people.