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

Initial reports suggested there were relatively few casualties in the attacks at a US consulate in Jeddah, a mosque frequented by Shi’ite worshipers in Qatif, and a security center in one of Islam’s holiest sites, the historic city of Medina.

The Medina attack apparently targeted Saudi security forces stationed near the seventh-century mosque of the prophet Mohammed, who is buried there.

Saudi Arabia’s Interior Ministry said four security officers were killed and five others were wounded when a suicide bomber detonated his vest in Medina, the Associated Press reported. No serious injuries were reported in the other Saudi attacks.

Monday’s attacks offered further evidence that in the three years since it declared the existence of its so-called caliphate, the Islamic State has developed the capacity to strike at will at the time of its choosing 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 coincide with the group’s declared enemies: Americans, members of the Shi’ite Muslim minority, and the Saudi security services.

The militant group, as it has in each of the previous three years, had urged its followers to carry out attacks during the holy Muslim month of Ramadan, a period of fasting, abstention, and prayer that will conclude on 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 the Ataturk Istanbul airport, a restaurant frequented by foreigners in the Bangladeshi capital Dhaka, and in Baghdad.

The vast majority of them — more than 200 people — died in the Baghdad blast, which targeted a shopping street packed with people out 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, Mohammed 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 he was directly linked to the group.

The Islamic State 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 of the Saudi explosions came Monday afternoon outside the closely guarded US consulate in the Saudi city of Jeddah, the first of the past week’s attacks directly to target a US facility.

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.

The US Embassy in Saudi Arabia said there were no casualties or injuries among the consular staff. The embassy said it remains in contact with Saudi authorities as they investigate the attack.

Hours later, a suicide bomber blew himself up near a mosque in the majority Shi’ite 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 gone home to break their fast.

The final attack came in Medina, the second-holiest site in Islam, which is visited by millions of Muslim pilgrims every year.

Local news media reported that two security guards died when at least one bomber detonated explosives near the Mohammed mosque. There was no immediate comment by the government, but a state-owned television station later broadcast footage of worshipers praying in the mosque, which was apparently unscathed.

Egypt, the United Arab Emirates, and Bahrain condemned the blasts in Saudi Arabia.

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