IN PICTURES: Manhunt for Boston blast suspect

Police walk down School and Walnut Street on April 19, 2013 in Watertown, Massachusetts. Earlier, a Massachusetts Institute of Technology campus police officer was shot and killed at the school's campus in Cambridge. A short time later, police reported exchanging gunfire with alleged carjackers in Watertown, a city near Cambridge. According to reports, one suspect has been killed during a car chase and the police are seeking another - believed to be the same person (known as Suspect Two) wanted in connection with the deadly bombing at the Boston Marathon earlier this week. Police have confirmed that the dead assailant is Suspect One from the recently released marathon bombing photographs. Photo/Darren McCollester/Getty Images/AFP This undated image released by the FBI shows Marathon bombing suspect Dzhokhar Tsarnaev, who is the subject of an April 19, 2013 manhunt in the Boston area. One of the Boston marathon bombing suspects was killed in a shootout early April 19 as police raced on a house-to-house search for Tsarnaev, with the entire city placed on lockdown. The two men believed to be responsible for Monday's deadly carnage at the finish line of the prestigious race are reportedly brothers of Chechen origin who were permanent legal residents of the United States. AFP PHOTO / FBI SWAT team members search for one remaining suspect at a residential building on April 19, 2013 in Watertown, Massachusetts. Photo/Mario Tama/Getty Images/AFP
Residents take pictures as they watch from windows while SWAT team members search for one remaining suspect at a neighboring apartment building on April 19, 2013 in Watertown, Massachusetts. Photo/Mario Tama/Getty Images/AFP SWAT team members prepare to search for one remaining suspect at an apartment building on April 19, 2013 in Watertown, Massachusetts. Photo/Mario Tama/Getty Images/AFP An elderly woman is evacuated from the School and Walnut streets area as police prepare to conduct a massive search for the one remaining suspect on April 19, 2013 in Watertown, Massachusetts. Photo/Darren McCollester/Getty Images/AFP Residents of an apartment building watch as members of the FBI, State Police, Boston Police, Cambridge Police, and other law enforcement agencies, survey the perimeter on April 19, 2013 near the home of suspect #2 on Norfolk Street in Cambridge, Massachusetts. Photo/Jared Wickerham/Getty Images/AFP Massachusetts Governor Deval Patrick (at microphone) with Boston Police Commissioner Ed Davis (L) speaks to the media at a shopping mall on the perimeter of a locked down area as a search for the second of two suspects wanted in the Boston Marathon bombings takes place April 19, 2013 in Watertown, Massachusetts. AFP PHOTO/Stan HONDA
Residents of an apartment building watch as members of the FBI, State Police, Boston Police, Cambridge Police, and other law enforcement agencies, survey the perimeter on April 19, 2013 near the home of suspect #2 on Norfolk Street in Cambridge, Massachusetts. Photo/Jared Wickerham/Getty Images/AFP
A woman reacts while being questioned by the FBI and other law enforcement agencies on April 19, 2013 near the home of suspect #2 on Norfolk Street in Cambridge, Massachusetts. Photo/Jared Wickerham/Getty Images/AFP
 A Massachusetts State Police officer checks the bag of a cyclist during heightened security on April 19, 2013 in Watertown, Massachusetts. Photo/Mario Tama/Getty Images/AFP