WATERTOWN, Massachusetts (Reuters) – Police on Friday killed one suspect in the Boston Marathon bombing during a shootout and mounted a house-to-house search for a second man in the suburb of Watertown after a bloody night of shooting and explosions in the city’s streets.

A national security official identified the hunted man as Dzhokar A. Tsarnaev, 19, and said the dead suspect was his brother, Tamerlan Tsarneav, 26. The brothers had been in the United States for several years, the official said.

WATERTOWN, Massachusetts (Reuters) – A police officer for the Massachusetts Institute of Technology was shot to death on Thursday night at the school’s Cambridge campus, touching off a manhunt in a community on edge just days after the Boston Marathon bombing.

Police descended on a vehicle in the neighboring Watertown community later in the evening amid reports of gunfire and explosions, the ABC TV station in Boston reported. One suspect was in police custody, local media reported.

BOSTON (Reuters) – President Barack Obama was due to visit Boston on Thursday to attend a memorial service for victims of the Boston Marathon bombing amid a manhunt for a suspect seen on video taken before two blasts struck near the finish line on Monday.

Obama will address an interfaith service and by extension the country following the blasts that killed three people and wounded 176 in the worst attack on U.S. soil since September 11, 2001.

BOSTON (Reuters) – Investigators of the Boston Marathon bombings believe they have identified a suspect from security video taken before Monday’s blasts killed three people and injured 176 others, a U.S. law enforcement source said on Wednesday.

The source said an official announcement was expected later on Wednesday in what is the first major publicly disclosed break in the investigation.

BOSTON, April 17 (Reuters) – The investigation of the Boston
Marathon bombing is focusing on a suspect or suspects believed
to have carried heavy bags or backpacks, but entered a third day
on Wednesday without any arrests or word on who was responsible.

Investigators appeared to have gathered enough evidence at
the crime scene on Tuesday to slightly narrow their search, but
it was also not known whether the perpetrators were domestic or
foreign, U.S. officials said.

BOSTON, April 17 (Reuters) – Boston Marathon bombing
investigators on Wednesday entered the third day of their hunt
with an emerging picture of the target: a suspect or suspects
carrying heavy bags or backpacks made of dark nylon.

While still unable to conclude whether a group or
individuals were responsible for the attacks that killed three
people and wounded 176, and whether they were foreign or
American, investigators gathered enough evidence at the crime
scene on Tuesday to slightly narrow their search.

BOSTON, April 16 (Reuters) – Authorities suspect whoever
perpetrated the Boston Marathon attacks carried heavy bombs made
from pressure cookers in nylon bags or backpacks to launch the
worst bombings on U.S. soil since security was stepped up
following the Sept. 11, 2001, hijacked plane attacks.

The twin blasts on Monday killed three people including an
8-year-old boy and injured 176 others, some of whom were maimed
by bombs packed with ball bearings and nails. Seventeen victims
remained in critical condition.

BOSTON (Reuters) – A pressure cooker stuffed with gunpowder and shrapnel caused at least one of the blasts at the Boston Marathon that killed three people and injured 176 others in the worst attack on U.S. soil since September 11, 2001, law enforcement sources said on Tuesday.

President Barack Obama called the two bombings on the marathon finish line an “act of terror” and police said parts of the center of Boston could be closed for days as they investigated the blasts that caused several people to lose limbs.

BOSTON, April 16 (Reuters) – President Barack Obama called
the Boston Marathon bombings an “act of terror” on Tuesday and
investigators said no additional explosive devices have been
found other than two that detonated near the finish line, a
development that could complicate the case.

Law enforcement officials, who asked the public to turn over
any photos or video of Monday’s marathon and the blasts, did not
disclose any possible leads in the investigation. No one has
been arrested, police said.

BOSTON (Reuters) – A Boston-area apartment was one focus of a wide-ranging police investigation on Tuesday as authorities pursued clues into who carried out a bombing attack that killed three people and wounded more than 100 others at the storied Boston Marathon.

Police overnight searched an apartment in Revere, about 6 miles (10 km) northeast of Boston, that was the residence of a person whose connection to the event is under investigation, law enforcement sources said.