IANAL, but I would caution against that advice. There is no conceivable way that NOT exercising your right to remain silent will help you. Your account can be given in a deposition, on a tape recorder, with your attorney present
I'm not recommending you jeopardize yourself legally. But whatever the legal aspects, they won't come in to play if you're dead from a police bullet. So, it's the immediate situation of being in an adrenaline rush with others who are in an adrenaline rush, all who have loaded guns, likely out and perhaps pointed at you, and all of whom are seeing you standing near an inert body and possibly with a gun. So, whatever you say or do has to solve that crucial predicament first. The legally apt statements and what they are are another thread I believe - though a very necessary topic. But how not to die comes first and my concern about that prompted me to start the thread.