I would opine that they started shooting right after saying “Drop he gun”. Which it would have to be proved to me they said. Just as soon as 50 or 75 backups got there, they started shooting. and high fived each other,”We got that Mexican son of a bitch”. Along the lines of the former Marine the SWAT murdered in his house in Arizona or maybe in new Mexico.
SOP. That is how they are trained now. Sometimes they forget to say, "Drop the gun!" but they always finish off by saying, "I felt threatened,"