Thank you for bringing this to my attention. Not sure exactly what kind of weapon it could be, it is very hard to hear. Do we in the video even hear anything or is that merely the cry of all the people? I expected to hear that very high pitched obnoxious beeping crowd control device that many have heard from the past years, but this is something different.
Here is a pertinent comment from a video by AP
2 days ago
i saw a square gray panel on a 2.5 or so meter tall pole not far away from where this happened about an hour and a half before this happened (at which point I was around 200 meters away from the event). A friend was in this crowd and told me he thinks that if the whatever it is they unleashed lasted a few seconds more many would likely have a heart attack. He felt a strange sensation in his heart and had a headache the whole day after the event. dont forget this was done from the back of a completely peaceful group of people in a middle of 15 minutes of silence they performed to honor the 15 people who died from shabby newly redone railway station many times over budget.