The six astronauts aboard the International Space Station are among the many people sending condolences to the people of Boston after two bombs went off at the finish line of the city's famous marathon today (April 15).
"Our crew just heard about the horrible events at the Boston Marathon. We all pass our condolences and thoughts to everyone affected," Expedition 35 commander Chris Hadfield said today via Twitter, where he posts as @Cmdr_Hadfield.
The cause of the explosions remains under investigation as of Monday evening. Boston police officials have confirmed that the blasts killed at least three people and wounded more than 100.