Authorities are investigating after two explosions went off at the finish line area of the Boston Marathon. The Fairmount Copley Plaza Hotel, the location all of the media room and some elite athletes, is currently on lockdown.

Approx 3:00pm ET:
Two explosions have been reported. Based on photos and videos the first explosion went off approximately 50 meters from the finish line close to the Marathon Sports store front on Bolyston Street. The second explosion went off about 13 seconds later about 150 meters down Boylston Street towards the Prudential Center. 

3:15pm:
Media room and race hotel is on lockdown. No one allowed to leave the hotel until further notice.

4:30pm
: 2 confirmed dead, 23 injured from the initial explosions. This number is subject to change as the injured are being diverted to Massachusetts General Hospital.

CBS4 reported that there were surveillance photographs before the explosions of a man who placed backpacks in trashcans. This is unconfirmed. All parcels dropped by the Boston Marathon finish line are all under investigation.

5:00pm: 
2 confirmed dead, 46 injured. Reported that a third device has gone off at the JFK Library. Flotrack has talked to Boston Marathon finisher and elite athlete Jason Hartmann who is safe at the hotel (see interview here).

5:20pm: 
Boston Marathon staff reports race facts and figures.
- 23,326 runners started marathon
- 17,584 runners finished the marathon
- 4,496 runners crossed the 40k mark but we diverted and never reached the finish line
- 1,246 runners never reached the 40k mark and were either stopped or dropped out 
- Time of last official finisher was 2:57pm

5:30pm:
2 dead, 51 injured. Initial reports of the explosion at the JFK Library may be incorrect. According to CBS, at 3:00pm this afternoon the fire alarm went off at the JFK Library. The alarm came from a wing of the library that's only two years old that mainly holds offices. There was an orderly evacuation followed by the presence of FBI and Secret Security agents.

5:35pm: 
There's a "chaotic scene" at Mass General Hospital. Security has been increased. Also, from the "The Daily Beat" Twitter


7:00pm: The lockdown has been lifted on the Fairmont Copley Hotel, so we're going to try and get out of here. Be safe, everyone. Also, earlier reports of possible suspect seem to be false.

7:45pm: Flotrack talks to elite athletes Kara Goucher (interview) and Diane Nukuri-Johnson (interview) about the events today and what it was like for the athletes while the news was breaking. All athletes are reported safe and in the hotel. Goucher heard the explosions from her hotel room and was visibly shaken up by the incident.

8:20pm: Video update #2 from Flotrack on site at the Boston Marathon. The crew is safe and we are heading away from the scene.
 


11:30pm: At this point the injury count is up to nearly 150, with 15 in critical condition and three people have now been reported dead including an eight year old boy. 

2:30am (Tues): At least 10 people had limbs that were amputated due to the explosions near the finish line.