Update: As the story of the killings in Mexico blows up in the American press, President Trump in a series of tweets offered American assistance in bringing the killers to justice. "If Mexico needs or requests help in cleaning out these monsters, the United States stands ready, willing & able to get involved and do the job quickly and effectively."
In other words, the US is determined to bring these killers to justice. Trump added that, after the rash of violent episodes in recent months, it's now time for Mexico to address its crime problem.
Trump also appeared to confirm that the family was caught in the crossfire between two feuding drug gangs.