Follow updates as Boston.com's Elizabeth Comeau tweets from the Boston Marathon medical tent:
Talked to a man who has family who was working medical tent that medical personnel have been moved to Beth Israel from the main tent location.
Am OK. Hunkered down a ways away from the explosion. I was walking away from finish line and was quite far when I heard the boom. Trying to get information about what's going on. I had gotten almost to Park Street when I heard the boom. At Park, they weren't letting anyone board the T. That's all I know for now. I hope my colleagues also covering the Marthon are safe. Thank you everyone for your messages. I am safe.
No regular updates from the medical tent staff this year in terms of how many people have been treated thus far or what the common ailments are since the extreme heat isn't a factor like it was last year. Reporters here at the tent don't have much to go on except our obsevations.
Most runners coming across look tired, but in good condition and far less are headed for the medical tent than last year at this point. There's a calmer atmosphere here at the tent this year compared to last, and everything seems to be operating like a well-oiled machine. A crowd of runners who crossed just behind her all gathered to catch a glimpse of Joan Benoit. Volunteers, too, peeked their heads out of the tent to see the former marathon champ give her post race interview. The sun is shining but there's still a slight breeze here at the finish. It's been a gorgeous day for a run.
We've seen men and women's wheelchair winners and now the women's winner Rita Jeptoo has rolled in.
Boston police just made sweep of grandstand with their dogs, spectators were carefully and tightly shuffled out of key areas and credentials were being checked at every stop along the finish line. Front of the medical tent is completely covered with just one opening in the tarp allowing a peek inside. Volunteers just wait now with most of the prep work done.
Good chilly marathon Monday!
I'm stationed here outside the main medical tent located just after the finish line. Last year, the medical tent had a spotlight on it, since temps were record-breaking. This year, temps are much cooler.
The volunteers who will escort any runners who are in need of medical attention are being briefed by marathon officials about where to take the athletes, and what to expect once runners start pounding in.
Follow @bewellboston for more ongoing updates throughout the day.