Not only that but the perpetrator is crowing about it on YouTube and other social media. He was more concerned about having to change his Twitter name. Absolutely no remorse. I'd call it 1st degree murder nothing less.
I'll double down on that one by saying most gamers know SWAT are trained killers that are more likely to use force than regular police. This is features in shooter games a lot. Especially in Call of Duty, the players have to regularly do "breaches" that hit a room SWAT-style with bad guys shot as quickly as possible. Many breaches also simulate chaos that happens where player initially has trouble identifying friend or foe.
A CoD player who isn't mentally impaired or something specifically sending in a SWAT team on a target who is shot by the team should be charged first degree at the start. Similarly for anyone else that clearly knew what a SWAT team does from games, movies, or other media. Prosecution might act mercifully from there depending on the circumstances. They better know they can do first-degree, though, with enough locked up to hopefully be a deterrent.