MIAMI — Lined up in front of their dugouts, all wearing No. 42 on Jackie Robinson Day, the Washington Nationals and Miami Marlins stood for a moment of silence to honor bombing victims at the Boston Marathon.

What began as an annual celebration to salute the man who broke baseball’s color barrier 66 years ago turned somber after a pair of explosions near the finish line in Boston — about a mile from Fenway Park — killed at least three people and injured more than 140 on Monday.

Hours later, Major League Baseball went on with ceremonies for the fifth Jackie Robinson Day at stadiums all over the country and in Toronto.

“Our thoughts and prayers are with everyone affected by this horrible occurrence and we are monitoring the situation,” MLB spokesman Pat Courtney said in a statement. “The safety of everyone that comes to our ballparks is always our top priority and we will continue to do everything to ensure a safe environment for our fans.”

There were moments of silence before each of the seven night games. At Great American Ball Park in Cincinnati, President Barack Obama’s remarks to the nation were shown on the video board while the Phillies were taking batting practice.

“I think everyone was thinking about it,” said Philadelphia outfielder Ben Revere, who taped the message “PRAY for Boston” on his glove. “It hurts to see something like that happen.”