Mariah Carey saddened by Boston blasts

Mariah Carey is at a "loss for words" after hearing about the tragic bombings in Boston.

Explosions went off at the finish line of the city's marathon yesterday, killing three people and injuring at least 144 more.

The senseless act of violence has shocked the world, with many celebrities taking to Twitter to offer their condolences and pray for the people affected.

"So sad I am at loss for words. My heart goes out to everyone in Boston. #PrayForBoston (sic)," Mariah wrote on the social networking site.

The hashtag #PrayforBoston circulated the micro-blogging network, with famous faces such as Justin Bieber, Selena Gomez and Rihanna all tweeting it.

Stars who grew up in the state of Massachusetts were particularly affected by the tragic incident, including Ben Affleck, whose father was an actor with the Theater Company of Boston.

"Such a senseless and tragic day. My family and I send our love to our beloved and resilient Boston (sic)," he posted.

Singer JoJo also grew up in the US state and expressed her shock after the news broke.

"Just got out of yoga and had a dozen text messages... My heart dropped. Please #PrayForBoston My Home. My family and dearest friends (sic)," she wrote.

It is not yet known who is responsible for the two explosions yesterday, but US President Barack Obama has vowed to get justice for America.

With the London Marathon approaching this Sunday, British police are "reviewing security plans", but the sporting event is scheduled to go ahead.