UPDATE -- Boston Marathon Explosion: Florissant Residents Ran in Race

NPR is reporting that two people have died and more than 100 are injured. The Associated Press reports two more explosive devices have been detected.

The AP also said that another explosion has taken place at JFK Library. 

Two explosions near the finish line of the Boston Marathon had people carrying bloody spectators into the medical tent set up for runners, according Back Bay Patch in Massachusetts.

"There are a lot of people down," the Associated Press quoted one man saying. The explosions happened about three hours after the winners crossed the finish line. 

The Boston Athletic Association website lists the following Florissant entrants:

• David Wilke
• Gary  Kleman

Reuters is reporting there are no indication how may people are injured, according to a story on the Chicago Tribune website, which also said the explosions happened as people were cheering on those still completing the race.

NBC News reported fire engines, police and emergency medical personnel were headed to the scene. An affiliate reporter told NBC News she heard two loud explosions, and that "everybody kind of ducked and hit the ground," and Jackie Bruno, reporter for New England Cable News said she saw people with significant injuries, including one person with a leg blown off.

"Runners were coming in and saw unspeakable horror," Bruno said.  

Patch is following this breaking story.