Story highlights Witness says crane toppled over during a "sandstorm which turned to rainstorm" 
 
 Saudi Civil Defense says via Twitter that storms caused the crane collapse 
 
 Mecca's Masjid al-Haram surrounds Islam's holiest site, the Kaaba 
 
 (CNN) A powerful storm toppled a construction crane Friday afternoon at the Masjid al-Haram, or Grand Mosque, in Mecca -- killing at least 107 people and injuring 238 others, Saudi Arabia's civil defense authorities said on Twitter. 
 
 Photos and video on social media showed the crane crashing through the mosque roof and the aftermath, with bodies, blood and debris spread across the courtyard. 
 
 The crane fell 10 days before the start of the Hajj , the annual pilgrimage expected to bring 2 million people to Mecca. The Masjid al-Haram is the largest mosque in the world and surrounds Islam's holiest site, the Kaaba -- a cube-shaped shrine that worshippers circle. 
 
 One man said the bad weather contributed to the chaos after the crane toppled over. 
 
 "We just washed and were getting ready to head to the Masjid al-Haram for the Maghrib prayer (sunset prayer)," said Yahya Al Hashemi, 30, a CNN iReporter who shot iPhone video of the crane striking the roof of the mosque. "It was a sandstorm which turned to rainstorm and lot of the construction covering boards were flying around, and lots of cracking noises which unfortunately ended with this tragedy. ... Everybody were pushing trying to escape from inside towards the exits." 
 
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 Media playback is unsupported on your device Media caption Unverified amateur footage appears to capture the moment the crane collapsed 
 
 At least 107 people died and more than 230 people were injured when a crane collapsed in the Muslim holy city of Mecca in Saudi Arabia. 
 
 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 defence said strong winds and heavy rains had caused the collapse. 
 
 Mecca is currently preparing for the annual Muslim Hajj pilgrimage. 
 
 Hundreds of thousands of people are expected to arrive in the Saudi city from all over the world later this month. 
 
 Image copyright AFP Image caption The crane was one of a number around the Grand Mosque while construction work is carried out 
 
 Image copyright AFP Image caption It collapsed during stormy weather 
 
 Image copyright AFP Image caption Emergency workers were quickly on the scene to deal with the high number of casualties 
 
 Image copyright AP Image caption This image shows the overturned base of the crane 
 
 The collapse happened at 17:23 local time (14:23 GMT), said Director-General of the Saudi Civil Defence Authority, Lt Sulayman Bin-Abdullah al-Amr. 
 
 It happened at a time when many worshippers were there for Friday prayers. 
 
 The toll for the dead and injured, tweeted by the Civil Defence Authority (in Arabic), continued to rise throughout the evening. 
 
 Media playback is unsupported on your device Media caption Footage shows the aftermath of the crane collapse in Mecca 
 
 Shortly before the crash, the city had been hit by unusually high levels of rainfall and winds of up to 83kph (50mph), Lt 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. 
 
 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. 
 
 Saudi authorities began a major expansion of the site last year to increase the area of the mosque by 400,000 square metres (4.3 million square feet), to allow it to accommodate up to 2.2 million people at once. 
 
 More than three million people undertook the Hajj pilgrimage to Mecca in 2012. Saudi authorities have taken steps since 2013 to limit the number of people involved. 
 
 Large numbers of people have resulted in several tragedies over the years, including a stampede in 2006 that killed nearly 350 people.
– A crane crashed through the roof of the Grand Mosque in the Muslim holy city of Mecca today, Saudi Arabia officials announced. The death toll from the tragedy currently sits at 65, the BBC reports. Details are few, but the crane collapsed as Mecca prepares for the yearly Muslim Hajj pilgrimage later this month. As CNN reports, the Grand Mosque or Masjid al-Haram is one of Islam's most important mosques; it surrounds the religion's holiest site, the Kaaba shrine, the destination of worshipers during the annual pilgrimage. Construction to expand the mosque has been ongoing for some time.