Steve Silva, a Boston.com reporter, was recording video of the marathon's finish line when two bombs exploded in short succession at 2:50 p.m. on Monday, April 15th.
Silva kept on filming and walked towards the explosion -- you can hear him saying "Oh my God, Oh my God, Oh my God" as he recorded. His footage was one of the first Boston Marathon bombing to be widely distributed and the YouTube clip garnered more than 9 million views in less than 24 hours. A Facebook photo he posted with the caption "God Help Us" also went viral.
You can also watch Silva's full video of the explosions here at Boston.com.