Update at 9 p.m.: After a violent, dramatic manhunt that effectively locked down Greater Boston, the sought-after suspect is in custody.

Editor's Note: After 11 a.m. Friday, we transitioned to a live blog format. For all of the day's updates after 11 a.m., see this post.

Update at 11 a.m.: "Though he's lived in the U.S. for five years, [Tamerlan] Tsarnaev says, 'I don't have a single American friend. I don't understand them.' " That's from a 2008 photo essay, "Will Box For Passport," of the now-deceased suspect. See page 18 of this PDF.

Update at 10:55 a.m.: Boston taxi service is back, police say.

Update at 10:32 a.m.: More from UMass-Dartmouth:



UMassD myAlert: Campus evacuation. Please leave campus calmly as soon as possible. Go to umassd.edu for more details. — UMass Dartmouth (@UMassD) April 19, 2013

Update at 10:12 a.m.: The University of Massachusetts Dartmouth says a student is being sought and the campus is closed. Here's the release:

UMass Dartmouth has learned that a person being sought in connection with the Boston Marathon bombing has been identified as a student registered at UMass Dartmouth. The campus is closed. Individuals on campus should shelter in place unless instructed otherwise.

Update at 10 a.m.: CommonHealth just hit publish on this: "Expert Offers Tips For Reassuring Children At Home In Lockdown"

Update at 9:41 a.m.: The MIT officer who was fatally shot last night has been identified:



Middlesex DA confirms MIT police officer Sean Collier, 26, of Somerville, was victim in last night's shooting. twitter.com/WBUR/status/32… — WBUR (@WBUR) April 19, 2013

Update at 9:15 a.m.: A new photo of suspect-at-large Dzhokar Tsarnaev, from the FBI:

Dzhokhar Tsarnaev (FBI)

Update at 9:08 a.m.: About a half hour ago, NPR identified the older brother as 26-year-old Tamerlan Tsarnaev.

Update on 8:37 a.m.: Here & Now host Robin Young just interviewed her nephew, who says he went to Cambridge Rindge and Latin School with Dzhokhar Tsarnaev, the suspect currently sought by authorities. "This is nothing that we'd even expect," her nephew (who we're not naming) said. He added that Tsarnaev was a "student-athlete." (Update at 9:37 a.m.: Here's the interview.)

Update at 8:15 a.m.: Authorities have issued this poster with the at-large suspect, Dzhokhar A. Tsarnaev, 19, of Cambridge:

Dzhokhar A. Tsarnaev, 19, of Cambridge

Update at 8:07 a.m.: Authorities just released the name of the MBTA officer who was shot while chasing the two suspects in a stolen vehicle from Cambridge to Watertown. Richard Donahue Jr., 33, is in critical but stable condition at an area hospital.

Update at 8:02 a.m.: In a brief statement, Gov. Deval Patrick added "all of Boston" to the earlier-announced list of communities with residents who should remain indoors.

Update at 7:30 a.m.: A third arrest, NPR says:



Third man has been arrested. He's being called an accomplice, not yet called a suspect, reports NPR's Dina Temple-Raston. — NPR News (@nprnews) April 19, 2013

Update at 7:20 a.m.: [This photo has been deleted since it contains images of investigators and could compromise their position.]



For more photos and videos of the overnight suspect manhunt, see here.

Update at 6:48 a.m.: In two tweets, the AP breaks potential details on the alleged bombers:

AP sources: Boston bomb suspects from Russia region near Chechnya, lived in US at least 1 year. Surviving Boston bomb suspect identified as Dzhokhar A. Tsarnaev, 19, of Cambridge, Mass.

WBUR has not confirmed the AP details.

Update at 5:57 a.m.: MIT has cancelled classes today. Harvard is also closed until further notice. Emerson too. Boston University is closed. BC too. Bentley's closed. Northeastern.

WCVB-TV's closings listing will keep updating.

Update at 5:51 a.m.: In a briefing, police just asked people in the following communities to stay indoors: Watertown, Newton, Waltham, Belmont, Cambridge, Allston/Brighton.

Update at 5:50 a.m.: All MBTA service is suspended until further notice, as officials continue their manhunt for the second marathon bombing suspect.



Update at 5:40 a.m.: Though officials at Beth Israel Deaconess Medical would not confirm it, a person, who is believed to be Suspect 1, was brought in after 1 a.m. with multiple traumas. He died in the hospital.

Update at 5 a.m.: To recap the primary details offered during a police briefing given in the 4 a.m. hour (all from law enforcement):

-- After 10 p.m. last night, a robbery took place at a 7-Eleven in Cambridge

-- After that, an MIT police officer was fatally shot, allegedly by the two marathon suspects

-- There was a carjacking in Cambridge involving the two suspects taking a Mercedes SUV

-- The car was discovered by police in Watertown, which led to an exchange of gunfire

-- During the chase, explosive devices were reportedly thrown from the suspects' car

-- During the exchange, one suspect was killed

-- Also during the exchange of gunfire, an MBTA officer was shot and is in critical condition

-- The second suspect fled and is at-large

-- There's an active search for the suspect who fled, the FBI's bombing "white hat suspect"

"We believe this to be a terrorist," Boston Police Commissioner Ed Davis said of the at-large suspect. "We believe this to be a person who's come here to kill people."

He advised everyone in the Watertown area to remain indoors and vigilant.

-- Here's the AP report on the developments overnight.

-- Here's the audio of this briefing:

Update at 4:20 a.m.: Boston Police tweets:



Per Commissioner Davis: One suspect deceased, 2nd suspect (white hat) at large & considered armed & dangerous. twitter.com/Boston_Police/… — Boston Police Dept. (@Boston_Police) April 19, 2013

Update at 4:05 a.m.: Boston Police Commissioner Ed Davis confirms they're looking for the marathon bombing suspects this evening (though it doesn't mean the dead suspect is the one in the black hat, from the FBI photos):



One suspect dead. One at large. Armed and dangerous. White hat suspect at large. — Edward Davis (@EdDavis3) April 19, 2013

Update at 3:55 a.m.: We reported earlier that police are investigating tonight's activity in relation to the marathon bombing suspects. While we do not have independent confirmation, multiple sources are saying:

-- Boston Globe: One suspect in Monday’s Boston Marathon bombings has been apprehended, according to an official with knowledge of the investigation. Another appears to remain on the loose in Watertown after a firefight with police. -- WCVB-TV: A suspect in the Boston Marathon bombings was killed early Friday morning, while the second suspect was being sought...

Update at 3:48 a.m.: An idea of the still-tense situation in Watertown:



Police will be going door by door, street by street, in and around Watertown. Police will be clearly identified. It is a fluid situation. — MASS STATE POLICE (@MassStatePolice) April 19, 2013

Update at 3:22 a.m.: Dave Procopio, State Police spokesman, offered these updates to WBUR's Fred Bever:

-- One suspect is "accounted for," and another is not accounted for,

-- and one transit officer was seriously wounded in the event.

Update at 3:22 a.m.: Full report from the AP on Watertown.

Update at 3:03 a.m.: State Police tell WCVB-TV...



WCVB reports @massstatepolicesee "strong link" to MIT murder, possible connection to Marathon bombings. — Adam Gaffin (@universalhub) April 19, 2013

Update at 2:45 a.m.: The Associated Press reports on Watertown:

Police have converged on a neighborhood outside Boston where there were reports of explosives being detonated and police are telling reporters to turn off their cell phones. Dozens of officers and National Guard members are in Watertown, where television outlets report that gunfire and explosions have been heard. A helicopter is circling overhead. Authorities early Friday were calling for somebody to get on the ground and put their hands up and a loud thud was heard after someone shouted "fire in the hole." Reporters are being told to move away from the scene. A police officer told a reporter: "If you want to live, turn off your cell phone." Earlier Thursday night a campus police officer was shot and killed at MIT and authorities were searching for the person responsible.

Update at 2:20 a.m.: Boston Police tweets:



There is an active incident ongoing in Watertown. Residents in that area are advised to remain in their homes. More details when available. — Boston Police Dept. (@Boston_Police) April 19, 2013

Update at 2:12 a.m.: WBUR's Curt Nickisch in Watertown:



In Watertown. Police vehicles going every which way. Boxy van with SWAT-looking guy inside drove by, armored Boston Rescue, too. — Curt Nickisch (@CurtNickisch) April 19, 2013

Update at 1:58 a.m.: Tweet from MIT:

MIT Police have determined that the suspect in this evening’s shooting is no longer on campus. It is now safe to resume normal activities.

Update at 1:53 a.m.: Statement from State Police spokesman Dave Procopio:

We are dealing with multiple scenes in Cambridge and Watertown. We do not yet know if there is any threat remaining at the Watertown scene. If you are there, please exercise caution. Right now I am at MIT. I do not know yet where we will be briefing from. It may still end up being here at MIT. I am working on that now as we are trying to get our arms around everything that has been going on. Please be patient.

Update at 1:26 a.m.: Heavy police presence is seen in Watertown on WCVB-TV's live coverage. Again, we're not sure of any connection to the fatal shooting in Cambridge.

Updated at 12:50 a.m.: The suspects are still at large, and the Cambridge Police scanner is reporting more shots fired in Watertown. It's not immediately clear if the suspects are the same as the Cambridge fatal shooting.

Live video coverage from WCVB-TV is here.

The shooting scene at MIT late Thursday night (Joe Spurr/WBUR)

Update at 12:22 a.m.: According to a statement from Cambridge Police, the officer was fatally shot while "responding to a report of a disturbance."

Update at 12:16 a.m.: More from the Middlesex DA's statement:

According to authorities, the officer was found evidencing multiple gunshot wounds. He was transported to the hospital and pronounced deceased.

There were no other victims in the shooting. No arrests have been made.

Update at 12:08 a.m.: The MIT officer has died, according to Cambridge Police.

Original post at 11:55 p.m.:

CAMBRIDGE, Mass. — A male Massachusetts Institute of Technology police officer has been shot and is suffering life-threatening injuries, according to State Police.

The shooting occurred at approximately 10:30 p.m. by campus Building 32 (Stata) near the intersection of Main and Vassar streets in Cambridge.

"No arrest has been made and the search for a suspect or suspects is ongoing," State Police said in a statement.

MIT issued a campus emergency alert at 10:48 p.m., saying "the situation is considered active and extremely dangerous." The university asked everyone to stay indoors and away from the surrounding area.

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