Strong winds were on Saturday blamed for knocking over a crane at one of Islam's holiest shrines in Mecca, killing 107 worshippers in what John Kerry described as a "horrific accident."
An investigation has been ordered into the disaster by Mecca's governor, Prince Khaled al-Faisal, according to Al Arabiya.
"Heavy rain and strong winds of unusually high speed led to the uprooting of trees, the fall of panels and the collapse of the crane," General Suleiman al-Amr, director general of the Civil Defense Authority, told the Saudi-owned channel.
The number of deaths may increase, al-Amr said. Many of the 238 people injured in the accident were only lightly wounded, he said.
It came at the start of the annual hajj pilgrimage, which has seen a string of deadly incidents including a 2006 stampede that killed hundreds.
In a statement, Kerry said it was "a horrific accident at such a peaceful place."
He added: "During this hajj season especially, the United States will stand with Saudi Arabia and all Muslims around the world in the aftermath of this dreadful incident at one of Islam's holiest sites."