It was a threat from several Muslim youth (one was Japanese and didn't appear Muslim via the usual routes, clothing/beard) in Arabic which thankfully she doesn't understand, we quickly left. Only to see on the news that day that about 4 girls were raped just next to where we were in quick succession.
This insane way of "surrounding a girl, then have another circle outside of the first circle to stop anyone from helping", much like the attacks which happened on New Years Eve in 2015 in Cologne (end of the year). The fact is this doesn't happen with any other culture in Europe with this frequency, and people are understandably sick of the media and PC people pointing towards the innocent ones as if it invalidates or negates said crimes.