A few minutes later, broadcasting manager Rob Brooks walked in to talk to him about plans for the game and found Kalas unconscious on the floor, his papers strewn around him.
Emergency medical technicians rushed him to George Washington University Hospital.
It was too late.
Harry the K, the Hall of Fame voice of the Phillies, was pronounced dead at around 1:20 p.m.
"Sadly, I must confirm that we've lost Harry," a red-eyed team president Dave Montgomery said shortly afterward in the eerie silence of the tunnel outside the Phillies clubhouse. "I've been with the Phillies for 39 years, and 39 years with Harry. As I said in this clubhouse, we lost our voice today. He has loved our game and made a tremendous contribution to our sport, and certainly to our organization."
There is no game scheduled today. When the team resumes play tomorrow night against the Nationals, their uniforms will feature a patch or armband in Kalas' memory.
Sadly, the Phillies have become adept at handling these situations. Beloved former player and broadcaster Rich Ashburn, Kalas' best friend, passed away after a game at Shea Stadium in September 1997. Beloved reliever Tug McGraw died in 2004. Respected coach John Vukovich was lost two spring trainings ago. Now Kalas.
Even before Montgomery's somber announcement, it was apparent that something had gone horribly wrong.
As word began to spread that Kalas had been taken to the hospital, the Phillies clubhouse was closed to the media. Montgomery had already arrived by then, his cab pulling up just as the ambulance was racing away.
Montgomery conducted a short team meeting, briefing the players on what was going on. The other broadcasters - Wheeler, Larry Andersen, Tom McCarthy, Scott Franzke, Gary Matthews, Danny Martinez, Bill Kulik - and Brooks filed solemnly into the room. Nationals president Stan Kasten and acting general manager Mike Rizzo also paid a visit.
By this time, Montgomery was in the process of contacting Kalas' wife, Eileen, and his three sons (Todd, Brad and Kane) before confirming the dread that everyone felt in the pit of their stomachs.
Kalas, who underwent heart surgery to implant stents in February, turned 73 a week before the Phillies broke camp in Clearwater this spring. But no official cause of death has been announced. And while shock and horror would have been the reaction under any circumstances, the timing of his passing was particularly cruel.
There was no bigger Phillies fan anywhere and his death came one day before the Phillies were scheduled to visit the White House to meet with President Barack Obama, one of the perks of winning the world championship. Montgomery said that, out of respect, that event has been canceled.
Also, while the players received their championship rings before last Wednesday's game at Citizens Bank Park, the rest of the team personnel, including broadcasters, aren't scheduled to get theirs until sometime in June.
The Nationals observed a moment of silence for Kalas before the first pitch and, before that, had offered to postpone the game.
"The Nationals were kind enough to come to us and indicate that they were willing to do whatever we felt was appropriate," Montgomery said. "We were appreciative of their sympathy, but I think we knew Harry would have wanted us to play."
After the game ended Montgomery, general manager Ruben Amaro Jr. and Gillick took questions in the interview room that Nationals manager Manny Acta uses for his postgame press conferences.
"It's going to take a long time to absorb the impact of [the loss of] Harry Kalas, not just on our organization and our ballclub, but also our city," Montgomery said. "What a gift he had and what a love for the game."
Amaro literally grew up with Kalas as his father, Ruben Sr., was with the Phillies when he was born. "He's been part of my life since I can remember listening to baseball games," the general manager said. "What I remember is him and Whitey [Ashburn]. This is a tragic loss, terribly sad.
"My biggest memory of him is hanging out in the back of the plane. He literally spent time with the players and was one of the guys. He became an integral part of the team. It was great after a couple years in the big leagues that I was able to graduate to the back of the plane with Harry."
Gillick first crossed paths with Kalas when he worked in the Astros front office. "He was a true professional," the senior adviser said. "You could hear the passion and the love for the game in his voice."
It was just another day. And then, without warning, it was anything but. *