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.
Officials said the suspects threw grenade-like bombs and fired guns at police during and after the chase. A transit policeman helping with the pursuit was seriously wounded. Officers shot Tamerlan Tsarnaev, the older of the two brothers, when he rushed toward them firing a gun. He was later found to have a small bomb strapped to his body. Emergency room doctors said he died from bullet and shrapnel wounds.
Dzhokhar Tsarnaev, described by the FBI as the "white cap" suspect in video and photo images from the marathon bombings scene, fled the shoot-out by speeding the carjacked SUV through police. Officials said he later switched to another car and then fled on foot.
The driver of the SUV said he was held hostage by the suspects for a half-hour. He said they told him they were the marathon bombers and that they had killed a police officer that very night. He was let go unharmed at a gas station after they had withdrawn $800 from an ATM with his bank card.
Authorities identified the MIT police officer killed Thursday night as Sean Collier, 26, of Somerville, Mass. The MBTA Transit Police Officer shot during the gunfight with the suspects is Richard H. Donahue Jr., 33, of Boston. He is in serious condition.
The suspects went from being unknown for four days after the marathon bombings to the details of their lives being broadcast around the world on Friday.
Officials said the family once lived in the predominantly Muslin region of Russia before coming to the United States in 2002 as refugees from the violence in Chechnya between residents there seeking independence and Russia. The parents later returned to Russia but the brothers and a sister stayed in the U.S.
The dead older brother, Tamerlan Tsarnaev, was reportedly married and the father of a 3-year-old daughter. He wasa a part-time student for three semesters at Bunker Hill Community College in Boston from 2006 to 2008, and was known for his boxing and martial arts skills. An acquaintance said he competed in Golden Gloves competition and talked about qualifying for the Olympics. The Boston Globe said he also commented in a photo essay posted to a social network that he "loved the USA" but also remarked, "I don't have a single American friend. I don't understand them." His profile said he quit smoking and drinking because of his Muslim faith.
The younger brother on the loose, Dzhokhar, was a star student at Cambridge Rindge & Latin High School, graduating in 2011. He was also a high school wrestler, and became a naturalized U.S. citizen Sept. 11 of last year. Classmates who knew him in high school told the Boston Globe he was friendly but not close to anyone. Students who knew him at UMass-Dartmouth also said he tended to keep to himself and did not talk about his Russian background. His father, contacted by the Russian news agency Interfax, said he was a medical student. But UMass officials said he was studying marine biology.