The President addresses the media after the arrest of the Boston bombing suspect (Getty Images)

The President addresses the media after the arrest of the Boston bombing suspect (Getty Images)

President Obama said that with the arrest tonight in Watertown, Mass. of Boston Marathon bombing suspect Dzhokhar Tsarnaev after an all-day search “our nation is in debt to the people of Boston.” Tsarnaev, 19, was taken into FBI custody shortly before 9 p.m. after hiding under the cover of a boat parked in a residential backyard.

“We’ve closed an important chapter in this tragedy,” Obama said in remarks at the White House about 10 p.m. But he noted there is still much work to be done in figuring out why and how two brothers became determined to attack a high-profile sporting event.

“We will determine how this happened,” he said. ” We will investigate any associations that these terrorists may have had.”

Tsarnaev, an American citizen of Chechen ethnicity who emigrated to the United States in 2000, was taken to Massachusetts General Hospital with multiple gunshot wounds. The Boston Police Department reported his condition as serious. Thousands of law enforcement officers tracked Tsarnaev to Watertown in a dragnet that forced the complete shutdown of the entire city of Boston, as well as the surrounding cities of Cambridge, Watertown, Waltham, Newton, and Belmont. Schools, universities, and public transportation were shut down all day while authorities searched for Tsarnaev.

Tsarnaev and his older brother, Tamerlan, were identified as suspects in Monday’s bombings by the FBI on Thursday evening. The massive pursuit began last night in Cambridge, when they were spotted at the Massachusetts Institute of Technology. They allegedly shot and killed campus police officer Sean P. Collier, the stole a car, instigating a high-speed chase. The pursuit continued into neighboring Watertown, where the Tsarnaevs engaged in another firefight with police. Tamerlan Tsarnaev, 26, died of wounds sustained in the early-morning scene, while a transit police officer was hospitalized with gunshot wounds.

“Boston Police and State Police and local police across the Commonwealth of Massachusetts responded with professionalism and bravery,” Obama said. He also eulogized Collier. “We also send our prayers, especially, to the Collier family who grieve the loss of their son and brother Sean.”

Though Dzhokhar Tsarnaev is in custody for allegedly setting two bombs at the finish line of the Boston Marathon that killed three and wounded 170, Obama noted the investigation is far from over. “Obviously tonight there are still many unanswered questions,” he said. “One thing we do know is that whatever hateful agenda drove these men to such heinous acts will not, cannot, prevail.”

Obama, appearing emotionally drained a day after he spoke at a memorial service in Boston, also noted the many rushes to conclusions made this week by the news and social media.

“In the age of instant reporting, tweets, and blogs, there’s a tendency to latch onto any bit of information,” he said. Throughout the day, White House officials monitored the situation in Watertown through official channels and with constant feeds of local television stations in Boston.

Obama also made note of the victims of a massive fertilizer plant explosion Wednesday night in West, Texas. “They are not forgotten,” he said of the explosion that killed 13 and injured more than 200.

“All in all, it’s been a tough week,” Obama said.

Full remarks:

Good evening. Tonight our nation is in debt to the people of Boston and the people of Massachusetts. After a vicious attack on their city, Bostonians responded with resolve and determination. They did their part as citizens and partners in this investigation.

Boston police and state police and local police across the Commonwealth of Massachusetts responded with professionalism and bravery over five long days. And tonight, because of their determined efforts, we’ve closed an important chapter in this tragedy.

I’ve been briefed earlier this evening by FBI Director Mueller. After the attacks on Monday, I directed the full resources of the federal government to be made available to help state and local authorities in the investigation and to increase security as needed. Over the past week, close coordination among federal, state, and local officials—sharing information, moving swiftly to track down leads—has been critical to this effort.

They all worked as they should, as a team. And we are extremely grateful for that. We owe a tremendous debt of gratitude to all our outstanding law enforcement professionals. These men and women get up every day, they put on that uniform; they risk their lives to keep us safe—and as this week showed, they don’t always know what to expect. So our thoughts are with those who were wounded in pursuit of the suspects and we pray for their full recovery.

We also send our prayers to the Collier family who grieve the loss of their son and brother, Sean. “He was born to be a police officer,” said his chief at MIT. He was just 26 years old. And as his family has said, he died bravely in the line of duty, doing what he committed his life to doing—serving and protecting others. So we’re grateful to him.

Obviously, tonight there are still many unanswered questions. Among them, why did young men who grew up and studied here, as part of our communities and our country, resort to such violence? How did they plan and carry out these attacks, and did they receive any help? The families of those killed so senselessly deserve answers. The wounded, some of whom now have to learn how to stand and walk and live again, deserve answers.

And so I’ve instructed the FBI and the Department of Homeland Security and our intelligence community to continue to deploy all the necessary resources to support the investigation, to collect intelligence, and to protect our citizens. We will determine what happened. We will investigate any associations that these terrorists may have had. And we’ll continue to do whatever we have to do to keep our people safe.

One thing we do know is that whatever hateful agenda drove these men to such heinous acts will not—cannot—prevail. Whatever they thought they could ultimately achieve, they’ve already failed. They failed because the people of Boston refused to be intimidated. They failed because, as Americans, we refused to be terrorized. They failed because we will not waver from the character and the compassion and the values that define us as a country. Nor will we break the bonds that hold us together as Americans.

That American spirit includes staying true to the unity and diversity that makes us strong—like no other nation in the world. In this age of instant reporting and tweets and blogs, there’s a temptation to latch on to any bit of information, sometimes to jump to conclusions. But when a tragedy like this happens, with public safety at risk and the stakes so high, it’s important that we do this right. That’s why we have investigations. That’s why we relentlessly gather the facts. That’s why we have courts. And that’s why we take care not to rush to judgment—not about the motivations of these individuals; certainly not about entire groups of people.

After all, one of the things that makes America the greatest nation on Earth, but also, one of the things that makes Boston such a great city, is that we welcome people from all around the world—people of every faith, every ethnicity, from every corner of the globe. So as we continue to learn more about why and how this tragedy happened, let’s make sure that we sustain that spirit.

Tonight we think of all the wounded, still struggling to recover. Certainly we think of Krystle Campbell. We think of Lingzi Lu. And we think of little Martin Richard. Their lives reflected all the diversity and beauty of our country, and they were sharing the great American experience together.

Finally, let me say that even as so much attention has been focused on the tragic events in Boston, understandably, we’ve also seen a tight-knit community in Texas devastated by a terrible explosion. And I want them to know that they are not forgotten. Our thoughts, our prayers are with the people of West, Texas, where so many good people lost their lives; some lost their homes; many are injured; many are still missing.

I’ve talked to Governor Perry and Mayor Muska and I’ve pledged that the people of West will have the resources that they need to recover and rebuild. And I want everybody in Texas to know that we will follow through with those commitments.

All in all, this has been a tough week. But we’ve seen the character of our country once more. And as President, I’m confident that we have the courage and the resilience and the spirit to overcome these challenges—and to go forward, as one nation under God, indivisible, with liberty and justice for all.

Thank you very much, everybody.