One suspect in the Boston Marathon bombings is dead, and at the time of our broadcast, a massive manhunt is underway for the second after a chaotic scene erupted overnight that left one police officer dead, another critically wounded. The Associated Press says the two men are brothers from a Russian area near Chechnya who had lived in the United States at least a year. The one still at large has been identified by the AP as Dzhokhar Tsarnaev, age 19, of Cambridge. Authorities released a new image of him on Friday. In a tweet, NBC News said the deceased suspect, described as suspect number one and seen in FBI-released photos wearing a black baseball cap, was Tamerlan Tzarnaev. A Massachusetts State Police official said the violence began when police received reports of a robbery at a convenience store near the Massachusetts Institute of Technology. An MIT police officer was then shot in his cruiser and later pronounced dead. The two suspects are then accused of carjacking a Mercedes SUV at gunpoint and, at one point, opening fire on police, including a transit officer, who is now in critical condition. During the firefight with police, the first suspect was injured and taken to Beth Israel Deaconess Medical Center, where he was pronounced dead. Dr. Richard Wolfe described the suspect’s injuries.

Dr. Richard Wolfe: “Multiple injuries, probably, we believe, a combination of blasts, potentially gunshot wounds.”

Journalist: “How many gunshot wounds?”

Dr. Richard Wolfe: “Unable to count.”

Journalist: “Multiple gunshot wounds?”

Dr. Richard Wolfe: “Yes.”

Journalist: “And the other — I’m sorry, I didn’t hear the rest of that.”

Dr. Richard Wolfe: “And probably a blast injury also.”

Journalist: “'Blast' meaning what?”

Dr. Richard Wolfe: “An explosive device, possibly shrapnel, thermal injury.”

Journalist: “Can you describe where it was?”

Dr. Richard Wolfe: “It was pretty much throughout the trunk. It was multiple wounds.”

The two suspects are accused of planting explosives that detonated within seconds of each other at the Boston Marathon on Monday, killing three people and injuring some 180 others. Amid the search for the second suspect, public transit service was shut down in Boston, and residents of the town of Watertown and the surrounding area were being told to stay indoors. This is Boston Police Commissioner Ed Davis.

Commissioner Ed Davis: “There’s a 20-block perimeter around the location that Chief Deveau just talked about. We are concerned about securing that area and making sure that this individual is taken into custody. We believe this to be a terrorist. We believe this to be a man who’s come here to kill people. We need to get him in custody.”

Last night’s violence erupted hours after the FBI released video and photographs showing the two suspects and called for the public to help identify them. They said one of the men — the one shown in a white cap who is still on the loose — was caught on camera setting down a black backpack at the site of the second explosion just minutes before the bomb went off. The images were posted to the FBI’s website, which was temporarily knocked offline as it was reportedly hit with its highest level of traffic ever.

On Thursday, President Obama spoke at an interfaith service at the Cathedral of the Holy Cross in Boston. He addressed the scores of people injured in the Boston Marathon bombings.

President Obama: “Our prayers are with the injured, so many wounded, some gravely. From their beds, some are surely watching us gather here today. And if you are, know this: As you begin this long journey of recovery, your city is with you, your commonwealth is with you, your country is with you. We will all be with you as you learn to stand and walk and, yes, run again.”

Two men who were not suspects in the Boston attack were featured on the cover of the New York Post Thursday with the headline “Bag Men” and the text “Feds seek these two pictured at Boston Marathon.” Following widespread condemnation, the Post’s editor-in-chief, Col Allan, said in a statement, “We stand by our story. The image was emailed to law enforcement agencies yesterday afternoon seeking information about these men, as our story reported. We did not identify them as suspects.” One of the men pictured, Salah Eddin Barhoum, is a high school student in the city of Revere who told the Associated Press he been scared to go outside after the cover appeared. Barhoum told ABC News: “It’s the worst feeling that I can possibly feel … I’m only 17.”

Salah Eddin Barhoum: “Everywhere I go, I just — like, I just don’t want to look at people, because when they look at me, they’re going to be like, 'Oh, you just did this. How could you do that?'”

Speculation about the backgrounds of those behind the bombings prompted at least two violent attacks. In the Massachusetts city of Malden, a Palestinian woman says she was assaulted and harassed Wednesday while walking with her infant daughter. Heba Abolaban told the Malden Patch a man punched her shoulder and launched into a profanity-laced tirade against Muslims, saying: “You are terrorists! I hate you! You are involved in the Boston explosions!” Meanwhile, a Bangladeshi man told the New York Post he was brutally beaten just hours after Monday’s bombings by a group of men who called him an “F-ing Arab” at a restaurant in the Bronx. Abdullah Faruque said his shoulder was dislocated in the attack.

Officials in Iraq say 32 people are dead and 65 wounded after a suicide bomber detonated explosives inside a cafe in the capital Baghdad. The cafe was reportedly packed with young people. Iraq has seen a rise in violence ahead of provincial elections that are set for Saturday.

The death toll from a massive explosion at a fertilizer plant in the Texas town of West remains unclear as officials continue to recover bodies from the blast site. On Thursday, officials said eight to 10 bodies had been recovered, and half a dozen more might be inside. The State Firemen’s and Fire Marshals’ Association reported five West firefighters were among the dead, as well as a Dallas firefighter and four medical personnel. The last time the Occupational Health and Safety Administration inspected the plant was reportedly in 1985.

Venezuela’s electoral council will complete an audit of presidential election results following calls for a recount by opposition candidate Henrique Capriles. Officials say they had already audited more than half of the vote but will now examine the remaining 46 percent. The United States has backed calls for a recount after Capriles contested the tight victory by Nicolás Maduro, chosen successor of the late President Hugo Chávez. Capriles claims the audit will show he won the election.

The co-sponsor of a measure aimed at expanding background checks for gun buyers is blaming the National Rifle Association for the bill’s defeat in the U.S. Senate this week. Senator Joe Manchin, a West Virginia Democrat who in the past has received a top “A” rating from the NRA, is now criticizing the group’s decision to grade lawmakers based in part on their votes on the background check measure, which failed to meet a 60-vote threshold Wednesday along with all other major gun-control proposals. Speaking Thursday at an event hosted by The Wall Street Journal, Manchin said his bipartisan compromise amendment, crafted with Republican Senator Pat Toomey, would have passed easily without the NRA’s decision.

Sen. Joe Manchin: “You know, if you’re going to score something, score the first one. The first one had Chuck Schumer’s bill, which I couldn’t vote for, OK? If you’re a gun-loving, Second Amendment defender, that’s the one you couldn’t even stomach. But I knew I had to get on that bill in order to change it. If they were true to their — you know, they said that we’ll score that one, and then this one makes sense, we won’t score this one.”

Gerald Seib: “What would have happened if they hadn’t scored it?”

Sen. Joe Manchin: “If they hadn’t scored it, it would have gotten 70 votes.”

An analysis by The Guardian and the Sunlight Foundation found all but three of 45 senators who torpedoed gun-control measures in the Senate this week have received money from firearms industry lobbyists. According to The Guardian, the NRA saw a spike in donations after the December shooting in Newtown, Connecticut, registering $2.7 million during January and February.

House lawmakers have passed a controversial cybersecurity bill that allows companies to share customer information with the government. The Obama administration has threatened a veto of CISPA, or the Cyber Intelligence Sharing and Protection Act, following public pressure from critics who say it would violate privacy rights. CISPA passed the House last year but was filibustered in the Senate. Companies including AT&T and Comcast have backed it, while critics including the American Civil Liberties Union mobilized against CISPA, saying it would “create a loophole in all existing privacy laws, allowing companies to share Internet users’ data with the National Security Agency, part of the Department of Defense, and the biggest spy agency in the world — without any legal oversight.”