A massive manhunt was under way Friday morning in Boston and its surburbs, after one suspect in the deadly Boston Marathon bombings died in a confrontation with police and the second was identified as a 19-year-old immigrant from Kyrgystan who, a classmate said, attended high school in Cambridge, Massachusetts.

Boston, Watertown and several other suburbs were in a state of lockdown, with mass transit canceled, schools and business closed and residents ordered to stay indoors, authorities said.

Law enforcement officials said they believe the at-large suspect, Dzhokhar Tsarnaev, may be strapped with explosives. They are taking extreme precautions in an effort to avoid further loss of life.