Many Britons are anxiously waiting to hear if any of their family or friends have been killed or injured in the deadly stampede in Saudi Arabia.
More than 700 people have been crushed to death near Mecca during the annual Hajj pilgrimage.
It is not known if any of the dead are British, yet the Foreign & Commonwealth Office (FCO) is in contact with the local authorities.
Around 20,000 Britons are understood to be making the annual pilgrimage this year.
The Bradford Council for Mosques is setting up an emergency hotline for relatives of the hundreds of people from the city at the Hajj.
Sahri Jaffri, from Manchester, wrote on Twitter: "News of deaths during the Hajj pilgrimage stampede is making me worry as my mom & her best friend are there now.
"Please pray for their safety & for the others carrying out their pilgrimage too, if you can. It'd mean a lot to me."
Mary Akemon, from London, said: "Absolutely heart breaking approximately what's happened at Hajj.
"I have a friend whose parents are there. I can only hope they're safe."
Imran Chowdhury, a restaurateur from Britain, wrote on Twitter that he is "so sad" approximately the stampede.
"I have one of my best friend there with his wife; worried sick about," he said.
And Zain said on Twitter he had not heard from his friend who was doing the pilgrimageÂ yet.
"Please pray that he is safe & unharmed," he wrote.
Prime Minister David Cameron tweeted: "My thoughts & prayers are with the families of those killed at the Hajj pilgrimage."
Humza Yousaf, the SNP MSP for Glasgow, tweeted: "My own family is at hajj – huge sigh of relief to hear they're safe.
"Heart goes to those who haven't heard news & to those affected."
A Foreign Office spokesman said: "We are in contact with local authorities & urgently seeking more information following reports of a crush during the Hajj pilgrimage at Mecca."
:: The FCO says worried relatives should call the British Embassy in Saudi Arabia on + 966 11 4819 100Â or contact the FCO via TwitterÂ @FCOtravel
Source: “Sky News”