Relatives scoured hospitals and pleaded online for news, fearing the worst after temperatures hit 51.8 degrees Celsius (125 Fahrenheit) in Mecca, Islam's holiest city, on Monday.
About 1.8 million people from all over the world, many old and infirm, took part in the days-long, mostly outdoor pilgrimage, held this year during the oven-like Saudi summer.
An Arab diplomat told AFP that deaths among Egyptians alone had jumped to "at least 600", from more than 300 a day earlier, mostly from the unforgiving heat.
That figure brought the total reported dead so far to 922, according to an AFP tally of figures released by various countries.
"The good news is that until now we did not find her on the list of the dead people, which gives us hope she is still alive."
Friends and family searched for missing hajj pilgrims on Wednesday as the death toll at the annual rituals, which were carried out in scorching heat, surged past 900.
www.france24.com
It's Hot as Hell in Mecca.