At least 87 people died and more than 200 people were injured when a crane collapsed on Friday in the Muslim holy city of Mecca in Saudi Arabia, the BBC reports.
The huge red crane crashed into a part of the Grand Mosque, the largest in the world, that was filled with worshippers at the time.
The head of Saudi Arabia's civil defense said strong winds and heavy rains had caused the collapse.
Mecca is currently preparing for the annual Muslim Hajj pilgrimage, to take place later this month, during which hundreds of thousands of people are expected to arrive in the Saudi city from all over the world.
The collapse happened at 5:23 p.m. local time, the Director-General of the Saudi Civil Defense Authority, Lt. Sulayman Bin-Abdullah al-Amr, was quoted by the BBC as having said.
It happened at a time when many worshippers were attending Friday prayers at the mosque. The toll for the dead and injured continued to rise throughout the evening.
Shortly before the crash, the city had been hit by unusually high levels of rainfall and winds of up to 50mph, Amr said.
A video posted on YouTube, which could not be independently verified, appeared to record the moment the crane fell, with a loud crash heard in the background followed by panic and shouting.
Images circulating on Twitter showed what looked like numerous bodies and blood on the floor of the mosque, according to the BBC.
Lt. Amr said an investigation was being carried out to assess the damage, and the "extent of the safety of these sites".
Mecca is preparing to welcome Muslims from around the world for the annual Hajj pilgrimage, which begins in about 10 days' time.
Islam requires that every Muslim capable of doing so performs a pilgrimage to the site at least once in their lifetime.
The tragedy comes amid a major expansion to the site, which began last year and which would increase the area of the mosque by 400,000 square meters (4.3 million square feet), to allow it to accommodate up to 2.2 million people at once.
(Arutz Sheva’s North American desk is keeping you updated until the start of Shabbat in New York. The time posted automatically on all Arutz Sheva articles, however, is Israeli time.)