MAKKAH: Saudi Arabia's King Salman vowed on Saturday to find out what caused a crane collapse that killed 107 people at Makkah's Grand Mosque ahead of the annual hajj pilgrimage. 

The hajj, a pillar of the Muslim religion which last year drew about two million faithful, will take place despite Friday's tragedy, Saudi authorities said as crowds returned to pray a day after the incident.

Hundreds of thousands of pilgrims had already arrived in Makkah when the massive red and white crane toppled over during a Friday thunderstorm.

"We will investigate all the reasons and afterwards declare the results to the citizens," Salman said after visiting the site, one of Islam's holiest.

Parts of the Grand Mosque remained sealed off on Saturday around the wreckage of the crane, which also injured around 200 people when it crashed into a courtyard.

But there was little mourning among pilgrims, who snapped pictures of the collapsed metal and continued with their prayers and rituals.

"I wish I had died in the accident, as it happened at a holy hour and in a holy place," Egyptian pilgrim Mohammed Ibrahim told. 

Om Salma, a Moroccan pilgrim, said "our phones have not stopped ringing since yesterday with relatives calling to check on us".

Indonesians and Indians were among those killed when the crane collapsed, while the injured included Malaysians, Egyptians, Iranians, Turks, Afghans and Pakistanis.

Salman expressed his condolences to the families of the dead, and then visited a local hospital "to check on the health of the injured", the official Saudi Press Agency said.

"Suddenly, I heard thunder and then we heard a very loud noise. That was the sound of the crane falling," Mohammed, a Moroccan pilgrim, told.