President Donald Trump was met with loud, sustained boos and chants of "Lock him up!'' from fans at Nationals Park when he was shown on the in-stadium video screen after the third inning of Game 5 of the World Series.

The boos ended only after the video screen cut to a shot of U.S. service members waving to the crowd and then showed a message thanking the military. Trump is attending the game with five wounded veterans.

Then, as Nationals starter Joe Ross took the mound to warm up for the fourth inning, fans started chanting, "Lock him up!'' in an apparent reference to ongoing impeachment proceedings against the president. Pro-Trump crowds have frequently chanted "Lock her up!'' about Hillary Clinton at the president's campaign rallies.

Trump was attending his first major league game since he took office in January 2017. He did not throw out the ceremonial first pitch and arrived with no fanfare just as the game began.

Trump's entourage in a lower-tier box to the left of home plate includes two Republican senators, Lindsey Graham of South Carolina and Florida's Marco Rubio. Also in the group is congressman Kevin Brady of Texas.

His arrival was not shown on in-stadium video monitors, but fans near the president turned and took pictures of him.

The Associated Press contributed to this report.