A massive manhunt is under way in Boston and the surrounding areas for this man, 19-year old Dzhokhar Tsarnaev, a suspect in Monday's deadly Marathon bombing.

All Boston public transportation and taxi service is shut down. Planes are grounded. The residents of the greater Boston area are told to remain indoors.

As of this writing, a SWAT team, with guns drawn and helicopters overhead, may have cornered the young Tsarnaev. Police are yelling into a house in Watertown, northwest of Boston, for Tsarnaev -- who is believed to be armed and dangerous, possibly with explosives on his person -- to give himself up. The FBI is on the scene, as are people in Army uniforms, most likely Massachusetts National Guardsmen.

This is believed to be an account for Dzhokhar Tsarnaev, believed to be of Chechen origin. People have been sending him "Gifts" of cop cars, bombs and bricks.

Last night, around 10:50 p.m., Dzhokhar and his older brother Tamerlan -- the two suspects identified by the FBI yesterday in connection to the bombings -- robbed a 7-Eleven and shot a responding MIT police officer dead. They then reportedly carjacked an SUV and drove to Watertown. Tamerlan -- whose YouTube account is, apparently, here -- was killed by police.

Right now, law enforcement is yelling into the house in Watertown for a man they believe is Dzhokhar Tsarnaev to come out.

We'll update this piece as more becomes clear. The manhunt for the Boston Marathon bombers looks like it's entering a critical phase. (See 6:25 p.m. update.)

Update, 9:19 a.m.: If the brothers Tsarnaev had to rob a 7-Eleven and steal a car to get out of town, that'll become a significant aspect of the investigation. It does not fit a pattern of a foreign-sponsored terrorist effort.

Update, 9:29 a.m.: National Guardsmen are moving into the 22-block Watertown radius where, reportedly, multiple locationss are under suspicion.

The Boston Globe reports that an "explosive trigger" was found on the corpse of Tamerlan Tsarnaev.

Update, 10:35 a.m.:

Unbelievable raw footage of the deadly shootout earlier today.

Update, 10:45 a.m.: Police and FBI in Boston say they're looking for a gray 1999 Honda with this license plate.

Update, 11:30 a.m.: Police say they've got the Honda CRV used by the brothers, abandoned in Cambridge.

The brothers' family members are urging Dzhokhar Tsarnaev to turn himself in. Ruslan Tsami, his uncle in Maryland, doesn't want Chechnya to be harmed by association with the bombers.

Anzor Tsarnaev, the brothers' father, told ABC News that he spoke with his sons this week. They discussed the bombing, but evidently didn't cop to it. "Give up. Give up. You have a bright future ahead of you. Come home to Russia," Anzor urged his sons. Then he added: "If they kill my second child, I will know that it is an inside job, a hit job."

All of this is feeling like a feedback loop on social media, with unencrypted Boston police scanners available on the web, getting tweeted about, and talking about tweets, and those remarks getting tweeted about.

Update, 12:40 p.m.: Still no apprehension, State Police Superintendent Timothy Alben told the press. There will be a "controlled explosion" in Cambridge later this afternoon at the Norfolk Street home where the brothers Tsarnaev lived.

Alben and Massachusetts Gov. Devals Patrick urged Watertown residents to stay indoors as the manhunt continues. Law enforcement continues going "door to door, street to street," Alben said, adding that they have new leads developing in the last several minutes.

Update: 4:10 p.m.: Massachusetts State Police tweet: "Suspects were in Civic, not CRV."

We've got a new reported piece for you about the new model manhunt, in which law enforcement embraces what the hivemind can provide.

Karen Anderson from Boston local WBZ-TV tweets some updated information, correcting an earlier misimpression: "Confirmed: the Armed Robbery was NOT the marathon bombers. The picture was from a gas station when they stopped bf car jacking."

Manhunt remains ongoing.

Update, 6:25 p.m.: The Boston lockdown is over. Without apprehending Dzhokhar Tsarnaev.

In a late-afternoon, news conference, Massachusetts Gov. Devals Patrick announced that he was no longer urging Boston, Watertown or Cambridge residents to stay indoors, "as long as you are vigilant." Mass transit will return. State Police Superintendent Timothy Alben said "we cannot continue to lock down an entire committee and an entire state. ... We do not have an apprehension of our suspect this afternoon. We will have one."

Alben appealed to Tsarnaev to give himself up. He said he believes Tsarnaev is still likely "in the Boston area." He revealed that, surprisingly, Tsarnaev is believed to have run away, "he fled on foot. I don't know where he went specifically." That escape occurred despite a large exchange of gunfire with police, and after Tsarnaev is believed to have run over his brother with a car.

Massachusetts authorities are likely to face big questions about their decision to lock down the city -- not something that New York did after the 2010 Times Square bombing attempt, or Washington D.C. did after the 2002 Sniper shootings. (I don't know how you scale up the Watertown effort to those sizes, but still.) I'm not playing Monday Morning Quarterback, but it's a decision that raises a lot of questions, especially since it didn't end with Tsarnaev in custody.

Update, 7:10 p.m.: It continues. Now shots are heard in Watertown. Boston PD tweets: "Police operations in the Franklin Street Watertown area. Residents shelter in place." The Boston Globe says Tsarnaev may be pinned down. CNN believes the same thing.

*Update, 7:52 p.m.: *Police evidently have Tsarnaev pinned down on a boat, and are lobbing flash-bang grenades at him. From the police scanner feed: "No movement."

Update, 8:47 p.m.: Suspect. In. Custody. Tsarnaev has been taken alive.

Now begins an inevitable debate -- signaled today by Sen. Lindsey Graham -- about charging and trying Tsarnaev in civilian or military custody. He's an American citizen, giving him the right to trial in a civilian court. Whatever the Obama administration chooses to do will face criticism. We've got emails out to see what its plans are.

NBC reports that Tsarnaev has been read his Miranda rights.

It is remarkable that law enforcement went from no leads to an alive, apprehended suspect after five days.