The singing of "The Star Spangled Banner" was by Jeffrey Kindwell, a representative of the investment firm Cantor Fitzgerald, which lost 658 employees on 9/11.
Marlins veteran infielder Wes Helms was playing for the Braves in 2001. What stands out to him in the aftermath was when the Braves and Mets resumed the season on Sept. 21 that year.
In an emotionally charged game, New York prevailed thanks to a Mike Piazza home run.
"We actually were the first team to play in New York," Helms said. "We played the New York Mets after we started back playing ball again. What stood out was Mike Piazza's homer against us, to win the game. To see the crowd and all the players' reactions during the national anthem. It was something you definitely remember."
This season, the Marlins are chasing a Wild Card dream while the Mets are on the verge of winning the National League East.
Players from both teams wore caps honoring police officers and firefighters.
Marlins manager Joe Girardi was playing for the Cubs at the time of the 9/11 attacks.
"We were out with the kids and a friend of ours called us and said, 'Turn on the TV,' " Girardi said. "It's probably the most horrific thing I think I've ever seen in my life. We kept the TV on, and it just got more and more depressing, everything that you watched.
"It was very difficult to go back to the ballpark. We were shut down a week. It just puts life into perspective. You thought maybe it was good for us to go to the ballpark because it might give people an outlet. You kind of went back and forth with it in your mind on what you should do."
Veteran reliever Matt Herges was pitching for the Dodgers then, and the wife of his former teammate, Shawn Green, called early in the morning.
"She said, 'Put on TV,'" Herges said.
Herges said one of his first reactions was to check up on his good friend, Paul Konerko, who was in New York awaiting the White Sox game with the Yankees on Sept. 11.
"I immediately called," Herges said. "The team was staying at the Grand Hyatt."
Herges believes Major League Baseball did its small part in the healing process of the country.
"It was pretty special, because I felt that baseball was helping the healing of our country," Herges said. "If it was being therapeutic to our country, I am honored to be part of that."