Thirty-five foreigners were killed and four injured when a bus collided with another heavy vehicle near Madinah, Saudi state media said on Thursday.
The accident on Wednesday involved a collision between "a private chartered bus with a heavy vehicle" near the western Saudi city, a spokesman for Madinah police said.
Those involved were Arab and Asian pilgrims, according to the Saudi Press Agency, which carried pictures of the bus engulfed in flames with its windows blown out.
The injured have been transferred to Al Hamna Hospital and authorities have launched an investigation.
Rulers of the emirates have sent messages of condolence to Saudi King Salman over the deaths of the pilgrims.
Expressing their condolences were: Sheikh Dr Sultan bin Muhammad Al Qasimi, Ruler of Sharjah; Sheikh Humaid bin Rashid Al Nuaimi, Ruler of Ajman; Sheikh Hamad bin Mohammed Al Sharqi, Ruler of Fujairah; Sheikh Saud bin Rashid Al Mualla, Ruler of Umm Al Quwain; and Sheikh Saud bin Saqr Al Qasimi, Ruler of Ras Al Khaimah.
The Crown Princes and Deputy Rulers also sent their condolences to King Salman.
British pilgrims were killed and 12 injured in Saudi Arabia when their bus collided with a fuel tanker in April 2018. They were on their way to the holy city of Makkah.
In January 2017 six Britons, including a two-month-old baby, were killed in a minibus on their way to Madinah after a pilgrimage to Makkah.
As part of efforts to diversify its oil-dependent economy, the conservative kingdom wants to foster a year-round tourism sector that includes millions of pilgrims.
Until last month, Saudi issued visas only to Muslim pilgrims, foreign workers and recently to spectators at sporting or cultural events, but tourists are now allowed to visit as part of the drive to prepare the biggest Arab economy for a post-oil era.