Overnight, the Boston Marathon bombing case has taken a significant turn. One suspect — suspect No. 1 seen wearing the black baseball cap from last night’s FBI photos and now identified as Tamerlan Tsarnaev — is dead after killing an MIT police officer and subsequently engaging in a shootout with authorities. The other suspect, his brother, identified as Dzhokhar A. Tsarnaev, is currently the subject of a massive manhunt in the Watertown, MA, area.

The Associated Press has identified the surviving bombing suspect as 19-year-old Dzhokhar A. Tsarnaev of Cambridge. His brother has been identified as 26-year-old Tamerlan Tsarnaev, who “was born in Russia” and “became a legal U.S. permanent resident in 2007.”

According to Peter Williams of NBC News, Dzhokhar was Born July 22, 1993 and attended Cambridge Rindge and Latin School. He has a Massachusetts drivers’ license and has been in the country for around a decade. CBS reported that he became a naturalized U.S. citizen on Sept. 11, 2012. He is a registered student at UMass Dartmouth, according to the school, where he lived in a dorm.

“A relative of the Boston Marathon bombing suspects said he repeatedly warned the 19-year-old fugitive Dzhokhar Tsarnaev about the bad influence of his older brother, Tamerlan Tsarnaev, who was killed overnight in a shootout with police,” reports The Boston Globe.

Ruslan Tsarni, the suspects’ uncle, said in a press briefing he’s “shocked” that the “children of his brother” could be associated with the Boston bombings. The last time he saw the brothers was December 2005.

In a press briefing at 12:35 p.m. Friday, Governor Deval Patrick and Mayor Tom Menino urged the Boston public to remain indoors. Col. Timothy Alben added, “Things change quickly. We’re going door to door, street to street.”

A friend of Dzhokhar’s told CNN that Dzhokhar was active in school with sports and a social life, and there was nothing to indicate this level “of darkness” in him. He said the brothers have been in the U.S. “six or seven years.” The Washington Post has reported that a “YouTube account that belongs to a person named Tamerlan Tsarnaev had bookmarked videos on terrorism.”

The brothers reportedly lived in Cambridge. A number of law enforcement and military officials are present in Watertown and Cambridge, near Norfolk Street. Specific locations are not being disclosed due to “a very fast and fluid situation.” CNN reports that Dzhokhar has not yet been located, but thinks he’s watching the news coverage: “If this guy comes out, he may come out and go down in a blaze of glory.”

“My son is a true angel,” the brothers’ father, Anzor Tsarnaev, said. “Dzhokhar is a second-year medical student in the U.S. He is such an intelligent boy. We expected him to come on holidays here.”

From public radio’s Robin Young: “My beloved nephew on right, djohar tsarnaev on left, happy cambridge Rindge and Latin grads. heartbreaking.”

CBS Boston, citing Connecticut State police officials: “Dzhokhar Tsarnaev may be driving a gray, Honda CRV with Massachusetts plates 316 ES9.” CBS Boston has reported that the vehicle has been found in Cambridge by state police and registered to Tamerlan.

In a press briefing Friday morning, State Police Spokesperson David Procopio said, “We believe they were in a CRV last night,” referring to the brothers, who reportedly spent the night in that car. Procopio furthered that suspect No. 2, Dzhokhar A. Tsarnaev (“white hat”) has not been apprehended.

In a video that’s since been taken down, Bloomberg TV released a video with a news anchor interviewing a man named Jon K., who said he knew deceased Marathon bombing suspect Tamerlan Tsarnaev from a local gym.

“About four or five years ago, I was working full-time as a project manager and in my off time, I was training at a mixed martial arts gym in Boston. Tamerlan wasn’t part of our gym, but he was training for the golden gloves boxing championship. I remember that he would come in to work with some of our boxers and worked with us. That is where I remember him from. When I woke up this morning and saw his name and his picture on the news, I immediately recognized him,” said Jon K., who wished to have his last last name omitted.

He continued: “He seemed like a really nice guy, to himself and a little bit arrogant and cocky, but he helped people at the gym all the time with their boxing and was friendly with everyone. It’s a complete shock. To see that this morning, all week, I have been wondering who the psycho was and it turns out that it was somebody I interacted with. It is shocking, especially as an athlete, he was an athlete, that he would do this to other athletes and just anyone in general. It is completely shocking to me. I would never expect it.”

Here’s the latest photo of Dzhokhar, the suspect still at large, and a link to his Russian social media profile:

And another sent to BostInno and reportedly from December 2011 at UMass Dartmouth:

Here he is as a young boy and this morning at the 7-Eleven:

Here are photos of older brother Tamerlan:

“With a bomb strapped to his chest, one of the Boston Marathon suspects was killed early Friday after he and his accomplice robbed a 7-Eleven, shot a police officer to death, carjacked an SUV and hurled explosives out the window in an extraordinary firefight with law enforcement,” reports NBC News. “”The bombing was very carefully planned but the getaway was full of holes,” said CNN.

Dzhokhar A. Tsarnaev remains at large and has been identified by police officials as a terrorist and is presumed armed and extremely dangerous. According to NPR news, a third man has been arrested and is being called “an accomplice.”

“We believe this to be a terrorist,’’ Boston Police Commissioner Ed Davis told reporters around 4:30 a.m. today of the suspect being sought by authorities. “We believe this to be a man here to kill people.”

“We believe these are the same individuals that were responsible for the bombing Monday at the Marathon,’’ State Police Colonel Timothy Alben furthered today. “We believe that they are responsible for the death of an MIT police officer and the shooting of an MBTA police officer. This is a very serious situation that we are dealing with.’’

NBC has also reported that the suspects are brothers of Chechen background “with the last name Tsarnaev,” according to information obtained from law enforcement officials. The suspect still at large is 19 years old and has a Massachusetts driver’s license. Law enforcement officials told NBC News that both men had international ties, had been in the United States about a year and had military experience, reports NBC.

Tamerlan Tsarnaev is the older brother and is believed to have been killed by explosives strapped to his body, CNN reports. He reportedly attended Bunker Hill Community College, years after his family left Chechnya. CNN reports that the older brother said “I don’t have a single American friend” on one of his social media pages. The brothers “are Islamic,” according to CNN. Tamerlan is reported as being very religious, not smoking or drinking.

Tamerlan has been training at Wai Kru Mixed Martial Arts in Allston as a boxer, as evidenced by this photo gallery titled “Will Box For Passport.” He was reportedly a two-time Golden Glove Champion. The younger brother, Dzhokhar, is said to be a great wrestler. Tamerlan’s former trainer at that studio described him as a nice guy, and said of the description of him being portrayed in the media, it is “not the person I used to know.”

The below photo depicts Tamerlan Tsarnaev, with the caption: “If he wins enough fights there, Tamerlan says he could be selected for the US Olympic team and be naturalized American. Unless his native Chechnya becomes independent, Tamerlan says he would rather compete for the United States than for Russia.”

Police this morning are searching a 20-block radius in Watertown for suspect No. 2, according to Boston.com. Currently all MBTA service has been suspended until further notice. Police have asked residents of Watertown, Waltham, Belmont, Allston-Brighton and Cambridge to stay indoors. All Boston residents should remain vigilant and cautious.

“We are asking you to stay indoors, to stay in your homes for the time being,’’ said Kurt Schwartz, who heads the state’s homeland security department, at a 6 a.m. press conference this morning. “We are asking business in those areas to cooperate and not open today until we can provide further guidance.’’