My preliminary analysis of the MN Pretti event based on all the videos I have seen:
1. While an agent was dealing with one protestor, Petti interfered with that agent, grabbing him by the back of his jacket.
2. Pretti's actions then cause other agents to swarm him and take him to the ground
3. An unknown agent see's Pretti's firearm and yells, "Gun, gun, gun!"
4. An agent in a gray jacket is able to remove the firearm and turns to move away
5. Based on the movements of that officer, it appear that Petti's firearm discharged, a known problem with early models of the Sig P320
6. After the initial discharge, you see the other agents suddenly jump back, as they do not know the firearm was taken, and they discharge their weapons.
This all happened in a matter of seconds. While an unfortunate accident, based on the totality of events, this was not a "cold-blooded m**der" as the left is claiming.