Apparently earlier in the day they were running a single track for awhile..
Yeesh. That's asking for trouble in a system as messed up as DC metro.
Here in Gotham, when they're reduced to one track, they tend to have one train ping-pong back and forth, just to be safe.
Reuters/NBC4 now reporting 55+ injured, including some with severe injuries.
http://www.reuters.com/article/newsOne/idUSTRE55L69G20090622