Boston and its surburbs, universities and transit system were on total lockdown Friday as police hunted for marathon bombing suspect Dzhokhar Tsarnaev -- on the loose after his accomplice brother was killed in a stunning chain of events that left one cop dead and another injured, officials said.

Authorities were confronting a double-edged nightmare: a ruthless killer at large in a densely populated area after a wild chase and firefights, and the possibility of other bombs. An explosive was found in Boston and disabled, an official said.

http://usnews.nbcnews.com/_news/2013/04/19/17823265-boston-on-lockdown-during-marathon-manhunt-for-white-hat-suspect?lite