Overnight — beginning about 2230 Boston time — the search for the Boston bombers unfolded into a fire-fight and active manhunt. The individual with a black hat shown in the photos released yesterday afternoon is evidently dead. As of 0530 Eastern on Friday the individual in the white hat is the object of an extensive search by a range of law enforcement agencies.
One of the best bets for authoritative reports is the Boston Globe website. According to the Globe:
The Associated Press reported this morning that the suspects came from the Russian region near Chechnya, which has been plagued by an Islamic insurgency. A law enforcement intelligence bulletin obtained by the AP identified the surviving bomb suspect as Dzhokhar A. Tsarnaev, a 19-year-old who had been living in Cambridge. The Globe has learned that the dead suspect is Tsarnaev’s brother.