More than 2,200 have died after Nepal's worst earthquake disaster in more than 80 years, police say.
Some 5,463 people have been injured.
From wacky costumes to knackered runners struggling over the finish line, the London Marathon has it all. Here's a collection of some of the best moments of the day - so far.
People were forced to run away from a landslide in Tibet after a powerful aftershock rocked Nepal and neighbouring regions following Saturday's deadly earthquake.
The London Marathon's celebrity contingent was strong this time around - most of them looking considerably better before they set out...
Marathon world record-holder Paula Radcliffe ran her last ever race today, finishing in an impressive 2:36:55.
She might have won the London Marathon three times in the past - once in a blistering 2:15:25 - but this time she was just happy to finish, to huge cheers from watching crowds.
"I didn't care about the time all the way round and I just wanted to thank as many people as possible," Radcliffe told the BBC.
"I went off way too fast and then it got more and more emotional. It was just amazing the whole way round."
After a hard-fought race, Kenyan Eliud Kipchoge won the 2015 men's London Marathon in a time of 2:04:42. He pipped his countryman Wilson Kipsang into second with a time of 2:04:47 - the fastest second place in London's history.
In third place was another Kenyan, Dennis Kimetto, with 2:05:50.
Ethiopian Tigist Tufa has romped home to victory in the London Marathon with a time of 2:22:21, ahead of Kenyan Mary Keitany in 2:23:40.
Sonia Samuels was the first Brit to finish.