BOSTON — A huge police dragnet spread across this metropolitan area Friday in search of the 19-year-old college student wanted for the Boston Marathon bombings after a night of chaotic gunfire that killed his companion suspect. A police officer was also killed and another seriously wounded.
"We believe this is to be a terrorist," said Boston Police Commissioner Edward Davis. "We believe this to be a man here to kill people."
He referred to Dzhokhar A. Tsarnaev, a student at the University of Massachusetts in Darmouth 40 miles south of Boston and a native of the Chechen region of Russia who became a naturalized U.S. citizen in September of last year.
He and his brother, Tamerlan Tsarnaev, 26, were identified Thursday afternoon in FBI video and photos as suspects in Monday's marathon blasts that killed three and injured 176. Both moved to the United States ten years ago with their parents.
The older brother died early Friday in a Boston hospital from gunshot and bomb fragment wounds received during a bloody police chase and gunfire exchange that ended in the suburb of Watertown on the west edge of the city.
The entire city of Boston and its close-in suburbs were locked down Friday, but the manhunt for Dzhokhar Tsarnaev focused on a 20-block area in Watertown. Heavily armed police in tactical gear searched door-to-door, aided by K-9 dog teams and armored vehicles on the ground and helicopters overhead.
The emergency security measures were unusual, with schools, banks, businesses and public transportation shut down tight. Few vehicles were on the streets. Residents were told to stay home and lock their doors.
"This is a serious situation," said Gov. Deval Patrick. "We are taking it seriously."
The massive manhunt was launched by two hours of violent events, starting Thursday at 10 p.m. in Cambridge, across the Charles River from Boston. Police responding to a 7-11 convenience store robbery in Kendall Square discovered an MIT campus police officer shot to death in his cruiser. A short time later, a Mercedes SUV carjacking nearby resulted in police pursuit and a shoot-out with the marathon bombing suspects in Watertown.