@cnn: President Donald Trump is attending Game 3 of the NBA Finals at Madison Square Garden as the Knicks look to take a 3-0 series lead over the Spurs. Security has been heightened around the arena, with a heavily secured perimeter surrounding several blocks around MSG ahead of Trump's arrival. Trump was loudly booed by sections of the crowd during the national anthem, drawing a stronger reaction than Spurs players received during introductions. Trump is also the first sitting president to attend an NBA Finals game. He was also the first sitting president to attend a Super Bowl when he traveled to New Orleans for the championship game last year. 📸: Samuel Corum/Getty Images; Mark Schiefelbein/AP; Saul Loeb/AFP/Getty Images; VVincent Carchietta/Imagn Images/Reuters; Charly Triballeau/AFP/Getty Images