That was not a uniformed police officer, the guy was wearing a suit.
An expensive suit too, from the looks of it.
Not typical law enforcement.
Don’t expect to learn the shooter’s identity anytime soon, if ever.
Another site said it was a Congressman.
I don’t think whoever it was had much experience with operating a firearm.
His stance and approach when he takes the shot seems a bit off. He acts like someone with little experience shooting firearms and ready to flinch at the loud noise he is about to make. Also his moves seem furtive, almost like a hesitant amateur assassin. Not like law enforcement who should at least be doing a little range time know and then.