(Image courtesy Dan Lampariello)

[UPDATE 5:] It is now being reported that three people, including an 8-year-old boy, have died. Over 150 people were injured in the blasts.

[UPDATE 4:] Boston Police have stated that the explosion at the JFK Presidential Library was fire-related.

[UPDATE 3:] A third explosion at the JFK Presidential Library is being treated by Boston police as potentially related to the first two explosions.

Amateur video of the explosions is now beginning to appear online:

[UPDATE 2:] It is now being reported that the explosions were caused by bombs and that more explosive devices have been found. Police are currently dismantling them. Police are treating bags abandoned at the scene as potentially dangerous.

Marathon runners who have not completed the race have been diverted to Boston Common

[UPDATE:] The Boston Police Department is currently reporting that 23 people have been injured and two people have died as a result of the explosions.

[ORIGINAL]
Two explosions have reportedly gone off near the finish line of the Boston Marathon. The cause of the explosions, which occurred near viewing stands on Boylston Street, has not yet been determined.

Reports from the scene of the explosions indicate that several people have been injured, some of them severely. Sean Kelly, a reporter for Boston news station WCVB has been tweeting updates on the situation since the explosions occurred and revealed that at least some of the injured have lost limbs:

Other citizens who were at the scene also took to social media, sharing video of the explosion and graphic pictures of the aftermath: