One such star was Bostonian Ben Affleck, who has performed and directed several films in his hometown.
Affleck expressed his emotions on Facebook Monday, posting: "Such a senseless and tragic day. My family and I send our love to our beloved and resilient Boston."
Affleck and his best friend, actor Matt Damon, who also grew up in Massachusetts, won an Academy Award in 1998 in for the film "Good Will Hunting." The movie was shot in the Boston area.
More on the Boston Marathon bombings: