It was in Madrid, 2013 when this happened.
Two friends and I were carrying huge backpacks each and just walking down the streets. Unfortunately we do not remember where exactly it happened, but there was a bunch of probably 10+ kids that ran towards us along this narrow path, which means there was no way to escape.
Thankfully, we smelled something amiss and quickly covered our pockets. After this bunch of kids ran past us, we didn’t have anything stolen.