Social media is exploding over the bloody impact of guns in America in the wake of the chilling assassination attempt against former President Donald Trump at a Pennsylvania campaign rally. The fact that Trump, surrounded by Secret Service agents and protected by snipers, could be shot and his face spattered with blood at the start of his address in front of thousands of spectators, underscores the extreme vulnerability to guns of the average citizen, including young schoolchildren, angry critics noted Sunday. Besides injuring Trump, shooter Thomas Matthews Crooks also killed a spectator and c…