It's Almost Impossible to Put an Entire U.S. Metro Area on Lockdown

CAMBRIDGE, Mass. — It's an intense and highly unusual morning here in the Boston metro area. Residents of Watertown, Newton, Belmont, Allston-Brighton, Cambridge, and all of Boston have been ordered by city and state officials to "shelter in place" while a massive manhunt for a second suspect in the Boston Marathon bombings, identified as 19-year-old Dzhokhar Tsarnaev, continues.

The metro area is being described as being "on lockdown." But what does being on lockdown actually mean in a major American city, where widely applied shelter-in-place protocols are virtually unheard of (and as CBS News points out, normally reserved for chemical or biological attacks)? The MBTA, the city's mass transit agency, has halted all service, and Boston taxi drivers have been ordered off the roads. Many local businesses and nearly all local schools and universities are closed. Still, a walk through the middle of Cambridge this morning shows just how difficult it is to actually enforce a citywide lockdown even in the most dangerous of circumstances.