Crowds of residents, clustered at barricades, kept a nervous watch of the police activity. Before noon, police waved through eight black vans, carrying agents.
Nancy Aiguier, who lived five doors down from the suspects, said she didn't know the brothers, but recognized them from photographs. She said they were always well dressed. The younger brother attended the same high school as her grandchildren, the prestigious Cambridge Rindge and Latin School, located a few blocks away on Cambridge Street.
"These are kids I've seen over the years," said Aiguier as she waited to return home. "I would have never guessed. They seemed like nice kids."
Her son, Troy Aiguier, owns a barbershop in the neighborhood and said he once cut the hair of the older brother, Tamerlan Tsarnaev.
"It's a shock," Troy said.
Even though most businesses in Boston were closed, Michael Borges of Inman Square felt compelled to get to his job as a technician at Mount Auburn Hospital.
Without regular transit, he had to walk to work. "I know we were told to stay in, but I feel I should come into the hospital in case something happens," Borges said.
With a manhunt for the younger brother, Dzhokhar Tsarnaev, continuing in Watertown, life around Boston came to a halt.
Schools and businesses shut down; universities canceled classes and conferences; hospitals went into a lockdown mode.
Streets in Cambridge were deserted as guards stood watch by the gates by Harvard Yard.
In the suburb of Watertown, frightened residents peered out their windows to see ranks of fully-armed police, followed by armored vehicles, patrolling past their front porches.
Fran Forman lives about half mile from where first bomber was shot in Watertown. She went out on her porch at 7 a.m. and saw helmeted troops in camouflage.
"There were a zillion cops and a SWAT team in full regalia," Forman said. "You never see these things in real life."
Four police came up to her porch to make sure her doors were locked and instructed Forman and her family not to leave.
"My husband screaming at me to get back in side," Forman said.
On Facebook, Larry Aaronson, a history teacher at the prestigious Cambridge Rindge and Latin School, wrote that he knew 19-year-old suspect Dzhokhar Tsarnaev, who graduated last year from the school.
"I took countless photographs of him on the wrestling team," Aaronson said. "And friends, here is the kicker...I knew this kid. He could not possibly have done this. He could not have been... a sweeter more gracious young man."
"I cannot believe he was capable of such a heinous crime and of so many murders," Aaronson said.
The history teacher said he came from the war zone deep inside Chechnya and moved here with his entire family. Aaronson said Tsarnaev lived three houses down from him in Cambridge.
"And now our whole block is cordoned off with yellow tape and we are living in a crime scene. When I was quoting that the war has come home yesterday to everyone, I did not mean it like this!!!!!!"
Contact Jennifer Lin at 215-854-5659 or firstname.lastname@example.org, or on Twitter @j_linq.