Major League Baseball tweeted from its official account, @MLB, "Our heartfelt thoughts and prayers are with those affected by the tragic events in Boston."
The Red Sox were en route to Boston's Logan International Airport when the news broke, and the club confirmed that the team has safely landed in Cleveland. Tweets from the players began to show that this news would shape the day and would not soon be forgotten.
"Praying for those effected [sic] by the explosions at the marathon," outfielder Jacoby Ellsbury tweeted, adding a hashtag of #Godblessboston. His teammate, Shane Victorino, tweeted, "Very sad to hear the news coming out of Boston. Horrific. My thoughts and prayers to all those involved."
The Red Sox were busy getting to Cleveland, but right outside the old ballpark, Bostonians could hear what was going on in Copley Square, just a few T stops from the Kenmore Square station that serves as the final stop for Sox fans on game day.
Sirens blared, helicopters buzzed overhead and televisions in the bars near Yawkey Way played out the inescapable images to sullen, teary-eyed viewers as others ran to attend to their suddenly altered lives with cell phones glued to their ears or raised aloft in attempts to get better signals.
"We were sitting at [a bar called] Who's on First," said Robert Francis Gailes, a Red Sox fan from Lee, Mass. "All of a sudden, we heard this bomb went off. Two of our friends have people running in the race."
Red Sox designated hitter and city icon David Ortiz hasn't been with the Red Sox lately. The man they call "Big Papi" is rehabbing the Achilles injury that ended his 2012 season early, and he weighed in from Pawtucket, R.I., where he's with the club's Triple-A affiliate working his way back to the Majors.
"I'm kind of angry," Ortiz said. "Whoever did this is insane. People are trying to raise money to get people healthy [by running the marathon]. This isn't a day to pick to do things like that. This is a big day for Boston and the nation in general.
"It's horrible when you see things like this happen. I'm watching the news and I can't believe it. I can't believe it."
Ortiz said he had been receiving text messages all day.
"I had people from my country [the Dominican Republic] texting me, asking am I OK, am I OK, am I OK?, because that's right around the corner from Fenway," Ortiz said. "'How is the family? We're watching the news and everything's going crazy.'
"It's a bad day, man."
Reds pitcher Bronson Arroyo was Ortiz's teammate in Boston and was well aware of what the Boston Marathon and the fanfare surrounding it meant to the city and its people. He remembers pitching against the Blue Jays on Patriots Day and ending up at the finish line, where he waited with teammates Curt Schilling and Mike Timlin, whose wives ran in the race.
"This is going to change the landscape of Marathon Monday in Boston, which is a huge deal," Arroyo said. "It's an event in Boston and close to home for everybody. It's definitely sad."
Down the hallway from Arroyo, in the visiting clubhouse at Great American Ball Park in Cincinnati and preparing for a game against the Reds, a one-time Boston celebrity now pitching for the Phillies sat in silence with his teammates in front of the TV and tried to put words to the shock, although the blasts hit home for him ... very close to home.
Jonathan Papelbon, who pitched for Boston for seven seasons, said he used to live above the Boston steakhouse Abe and Louie's, located near the scene of one of the two deadly explosions, which The Associated Press reported took place about 100 yards from each other by the crowded finish line and resulted in an unspeakable scene of carnage.
"It's sad, man," Papelbon said. "Patriots Day is a big thing in Boston. Sox play at 11 o'clock. It's all ruined. Families are ruined, lives are ruined. For what? It's just sad.
"I'm looking at it right now and I'm like, 'Damn, I used to live right there.'"
Papelbon had not been able to reach friends and loved ones in the city, and he admitted that the situation is hard to even fathom right now.
"It's kind of surreal," he said. "I don't know man, it's crazy. ... Hopefully the city can rally and make things better, but it's going to be tough."
Oakland A's first baseman Nate Freiman knows that city well. He grew up in Wellesley, Mass., which is the halfway point of the marathon, and he spent many a Patriots Day morning downtown watching the runners go by.
"It's such a huge deal, a big day there," said Freiman, who was in constant contact with friends and family members all day. "It's just awful what's happened."
Mets reliever Scott Atchison pitched for the Red Sox last year and couldn't help but remember leaving the stadium via a different route on Marathan Monday because the roads to his home were blocked off.
"I still know so many people that are right there in that area," Atchison said. "But as far as I know, everybody was all right that we know."
Padres manager Bud Black also was fortunate. While en route to Dodger Stadium, where his team and the Dodgers were set to honor the life, legacy and impact on society of Jackie Robinson and then play a game, he learned of the explosions. His daughter, Jamie, lives two blocks from Fenway and Black could not get through to her when he tried to call her at first. He did, however, reach her by text and found out she was OK.
Elsewhere around the big leagues, players were chiming in with their prayers, condolences, sadness and shock. Several Dodgers, for example, offered their thoughts via Twitter.
"Thoughts and prayers to all of the victims and families of the #bostonmarathon," tweeted reliever Brandon League. "Sick Sad World."
Outfielder Matt Kemp tweeted, "Prayers go out to all affected by the explosions in Boston. #PrayForBoston," while his teammate, former Red Sox first baseman Adrian Gonzalez, tweeted, "My prayers go out to the city of Boston! #prayforboston."
Nationals manager Davey Johnson was far away from the site, readying his club for a game against the Marlins in Miami, and he communicated the collective feelings of all of baseball in light of such a sobering real-life event: that baseball is a game and a pastime, and it all seems unimportant on days like this.
"It's just a terrible tragedy," Johnson said. "Kind of brings things into perspective. It's the world we live in. That's the tough part. But we've got to go out there and perform, do our job."
White Sox manager Robin Ventura echoed the sentiments shared by many when asked for his thoughts.
"I think it just always boggles your mind and you scratch your head," Ventura said. "It doesn't make any sense, ever. It's just sad. I think anytime you see something like that, there is just no reason for it."
Twins skipper Ron Gardenhire agreed, struggling to find words to describe it.
"It's sad to see," Gardenhire said. "I guess we'll find more in the coming days what this all means. But it's sad. People were just enjoying a race."
For Rockies relief pitcher Adam Ottavino, the events of Monday served as a stark reminder to Sept. 11, 2001. Ottavino went to Berkeley Carroll High School in Brooklyn and was a sophomore that day.
He said he hopes, after a necessary period of grief and mourning, that people will soon resume their daily routines without fear of what might happen randomly while enjoying the fruits of freedom in public places.
"One of the worst things you can do is to hide and be scared, not live your life," Ottavino said. "One of the big moments from 9/11 was when people started getting back to normal lives, playing baseball again, things like that. It's good for America."