Three suicide bombers struck across Saudi Arabia on July 4 as Muslims celebrated the final days of the holy month of Ramadan. (Reuters)

Suicide bombers suspected of links to the Islamic State struck for the fourth time in less than a week, targeting three locations in Saudi Arabia in an extension of what appeared to be a coordinated campaign of worldwide bombings coinciding with the Muslim holy month of Ramadan.

The triple attacks Monday ranged across the kingdom: near a U.S. consulate in Jiddah, a mosque frequented by Shiite worshipers in an eastern district, and at a security center in one of Islam’s holiest sites, the historic city of Medina. The Saudi Interior Ministry told the state-run television station that four security guards died in the Medina attack and five were injured.

The attacks offered further evidence that in the two years since it declared the existence of its so-called caliphate, the Islamic State has developed the capacity to strike at will in diverse locations around the world.

There was no immediate claim of responsibility, but the bombings bore the hallmarks of the Islamic State, with suicide attackers picking targets that closely coincided with the group’s declared enemies: Americans, members of the Shiite Muslim minority and the Saudi security services.

On Tuesday, the Saudi Interior Ministry identified the bomber behind the Jiddah attack as a 34-year-old Pakistani, Abdullah Qalzar Khan, who it said arrived in the kingdom 12 years ago to work as a driver. The statement gave no other immediate details.

The United States condemned the violence in Saudi Arabia and vowed to stand with the Saudi people against terrorism. “These attacks underscore the scope of the threat we all face, and remind us of the need to continue to stay focused on combating violent extremism and bringing those responsible for it to justice,” State Department spokesman John Kirby said in a statement Tuesday.

The Islamic State, as it has in each of the three years since it announced its existence, had urged its followers to carry out attacks during the holy month of Ramadan, a period of fasting, abstention and prayer that will conclude Wednesday with a holiday of feasting and family visits.

This has turned into the most blood-soaked Ramadan yet in the Islamic State’s campaign. At least 290 people have been killed in attacks claimed by or linked to the Islamic State — at Istanbul Ataturk Airport, at a restaurant frequented by foreigners in the Bangladeshi capital, Dhaka, and in Baghdad. The vast majority of them, 222 people, died in the Baghdad blast, which targeted a shopping street packed with people celebrating the end of the day’s fast and shopping for the approaching holiday.

Omar Mateen, the gunman who killed 49 people at an Orlando nightclub last month, may also have been inspired by the call for Ramadan attacks issued by the Islamic State’s chief spokesman, Abu Muhammad al-Adnani, in late May. But although Mateen cited the Islamic State as his inspiration in phone calls to emergency responders, investigators have found no evidence that he was directly linked to the group.

The Islamic State also did not claim the attack in Istanbul, but Turkish investigators say the group is the leading suspect.

The attacks in Saudi Arabia raised concerns that the group is taking deeper root there, potentially threatening the stability of one of America’s closest Arab allies. The Islamic State has frequently threatened the kingdom, whose status as the guardian of the holiest sites in Islam is challenged by a group that regards itself as the rightful leader of the Muslim world.

The first blast came in the afternoon outside the closely guarded U.S. Consulate in the city of Jiddah, the first of the past week’s attacks to target a U.S. facility directly. Two security guards were wounded, and the bomber died, after security guards approached the man and he detonated his explosives, according to the state-run Saudi Press Agency.

Hours later, a suicide bomber blew himself up near a mosque in the majority-Shiite city of Qatif in eastern Saudi Arabia. A resident of the city contacted by the Reuters news agency said there appeared to be no casualties other than the bomber, because worshipers had already gone home to break their fast. The Islamic State in the past year has claimed a number of deadly bombings against the Shiite minority in Saudi Arabia.

The final attack came in Medina, the second-holiest site in Islam, which is visited by millions of Muslim pilgrims every year. It apparently targeted Saudi security forces stationed near the 7th century Prophet’s Mosque, where the prophet Muhammad is buried.

The Saudi Interior Ministry told the state-run news channel that the attacker detonated the bomb when security officers raised questions about him, the Associated Press reported. The station later broadcast footage of worshipers praying in the mosque, which was apparently unscathed.