'We will go to the ends of the earth'

Boston Police Commissioner Edward Davis spoke along with other local and federal officials Tuesday morning.

Bill Greene/Globe Staff

Boston Police Commissioner Edward Davis spoke along with other local and federal officials Tuesday morning.

Senator Elizabeth Warren, Boston Mayor Thomas M. Menino, Governor Deval Patrick, and FBI special agent in charge Richard DesLauriers spoke at the press conference.

Elise Amendola/Associated Press

Senator Elizabeth Warren, Boston Mayor Thomas M. Menino, Governor Deval Patrick, and FBI special agent in charge Richard DesLauriers spoke at the press conference.

Roads around Boylston Street in Boston's Back Bay were closed and considered an active crime scene on Tuesday morning.

Dina Rudick/Globe Staff

Roads around Boylston Street in Boston's Back Bay were closed and considered an active crime scene on Tuesday morning.

Another look at the scene around Boylston Street on Tuesday.

Dina Rudick/Globe Staff

Another look at the scene around Boylston Street on Tuesday.

Boston Police officers stood near the finish line of the Boston Marathon on Tuesday morning.

JUSTIN LANE/EPA

Boston Police officers stood near the finish line of the Boston Marathon on Tuesday morning.

A police officer stood guard at the corner of Boylston Street and Arlington Street early Tuesday.

Darren McCollester/Getty Images

A police officer stood guard at the corner of Boylston Street and Arlington Street early Tuesday.

Neighbors left flowers outside the Dorchester home of the eight-year-old killed during the attack.

Evan Allen/Globe staff

Neighbors left flowers outside the Dorchester home of the eight-year-old killed during the attack.

A military police officer checked the identification of a man on Massachusetts Avenue on Tuesday morning.

Darren McCollester/Getty Images

A military police officer checked the identification of a man on Massachusetts Avenue on Tuesday morning.

Overnight, a wave of law enforcement officials swarmed a home of a

Matthew J. Lee/Globe Staff

Overnight, a wave of law enforcement officials swarmed a home of a "person of interest" on Ocean Avenue in Revere.

FBI and Homeland Security agents were seen entering the Water's Edge apartment complex at 364 Ocean Ave.

Matthew J. Lee/Globe Staff

FBI and Homeland Security agents were seen entering the Water's Edge apartment complex at 364 Ocean Ave.

Police units assembled along the Boston Public Garden  on Tuesday morning.

Darren McCollester/Getty Images

Police units assembled along the Boston Public Garden on Tuesday morning.

Special police units assembled in the Boston Common on Tuesday morning.

Darren McCollester/Getty Images

Special police units assembled in the Boston Common on Tuesday morning.

A woman received help following the first of two explosions on Boylston Street Monday.

JOHN TLUMACKI/GLOBE STAFF

A woman received help following the first of two explosions on Boylston Street Monday.

Just seconds after the first explosion rocked the area near the finish line, there was a second blast a few blocks away on Boylston Street.

DAVID L. RYAN/GLOBE STAFF

Just seconds after the first explosion rocked the area near the finish line, there was a second blast a few blocks away on Boylston Street.

Boston Marathon Bombings

Officials seek public's help

Doctors said that objects appeared to have been intentionally placed into the bombs to inflict shrapnel wounds. At least 176 were injured and 3 killed.

Roommate defends man questioned in blasts

“I don’t think he could do that,” the roommate said of the Saudi Arabian man, adding that law enforcement are still in his Revere apartment.

In response to the marathon bombing, Senate Minority Leader Mitch McConnell said Americans have lowered their guard.

McConnell says America has become 'complacent'

In response to the marathon bombing, Senate Minority Leader Mitch McConnell said Americans have lowered their guard.

Martin Richard

Neighbors mourn boy, 8, killed at Marathon

Martin Richard was killed and his mother and sister seriously wounded as they waited for their father to finish the race.