US police said it killed one of the Boston marathon bombing suspects in a shootout early Friday and pursued a chaotic street-to-street manhunt for the second.

US police said it killed one of the Boston marathon bombing suspects in a shootout early Friday and pursued a chaotic street-to-street manhunt for the second.

NBC News reported that “the two young men believed to be responsible for Monday's carnage at the finish line of the prestigious race are brothers of Chechen origin, who were permanent legal residents of the United States.”

The two men, dubbed "Suspect One" and "Suspect Two" by the FBI, led police on a violent cavalcade that left inhabitants of towns around Boston cowering in their homes as gunfire and explosions erupted through the night.

The city and its immediate suburbs were effectively shut down, with public transport suspended throughout the region and all schools closed as police chased the second suspect, identified by NBC as 19-year-old Dzhokhar Tsarnaev.

One police officer was killed and another wounded in the operation, Boston Police Commissioner Ed Davis said, confirming that the dead man was Suspect One as labeled in photos released by the Federal Bureau of Investigation (FBI).