Today’s bombing near the finish line at the Boston Marathon will set off a domino effect of transit security measures in cities across the U.S., but in Boston, New York City, and Washington, D.C. in particular.

Twitter is proving to be the most timely resource for information out of these cities. Just seconds ago, the FAA lifted the ground stop at Boston Logan airport:

Photo Credit: Boston's Green Line trains, which are currently not in service because of the Marathon bombing. Wally Gobetz / Flickr