Heartbreaking for my son who saw the police as attackers coming to kill us

I had taken my 5 year old son with me on that Friday for a teachable moment on speaking up when those in authority abuse their powers. I had explained to him about the situation with a black man in Minnesota who was murdered by a police officer. I also explained to him that not all of the police are bad, but it was important to speak out.
The protest itself was peaceful with people chanting and holding up signs wanting justice for Floyd. We were there for about an hour, and the rain had started, and my son was tired as it was already late for him. I crossed the street to Freimann Square where we waited under a tree for the rain to let up.
Seconds later the police on full riot gear came marching up Clinton street and immediately started what looked like to me gassing the crowd. No warnings, no call to vacate, nothing. As the mace and gas was shot, it hit both me and my boy. Immediately my son started coughing and and I grabbed him to run away from the attack on the protesters. I had to stop because I too was getting the effects of gas and was trying to put our masks up to try and help with the effects.
It was heartbreaking for my son who saw the police as attackers and was crying about the men were coming to kill us. It was awful.