Weekly Address: Marathon Bomber & Texas Explosion [VIDEO]

President Barak Obama pledged to seek answers for the victims of the Boston Marathon explosions about the motives and the planning behind the deadly blasts, even as he acknowledged that the capture of a second suspect brought to a close a trying five days for his presidency and for the nation.

"All in all it's been a tough week," he said. "But we've seen the character of our country once more."

The marathon blasts and the hunt for the suspects that both terrorized Boston and captivated the country were the predominant worries at the White House. But the capture of one suspect Friday, following the death in a shootout of another, capped an extraordinary week in Boston, Washington and elsewhere around the country.

A massive explosion leveled a Texas fertilizer plant Wednesday, leaving at least 14 people dead, 200 injured and a staggering 60 others still unaccounted. On Tuesday, letters addressed to Obama and to a U.S. senator were found to contain traces of poisonous ricin. An Elvis impersonator was arrested and charged with threatening the president's life.

"Resilience & spirit to overcome"

"I'm confident that we have the courage and the resilience and the sprit to overcome these challenges and to go forward," Obama said late Friday at the White House, just over an hour after law-enforcement officials apprehended 19-year-old Dzhokhar Tsarnaev as a suspect in Monday's explosions at Boston's venerable race.

Three people were killed and more than 180 injured in the blasts. A Massachusetts Institute of Technology policeman was killed and another police officer was severely wounded during the manhunt .

Tsarnaev's older brother, 26-year-old Tamerlan Tsarnaev, was also wanted in the bombings and died earlier Friday in an attempt to escape police. The two men were identified by authorities and relatives as ethnic Chechens from southern Russia who had been in the U.S. for about a decade.

Both Obama and Republicans used their weekly addresses to celebrate the resolve Americans demonstrated after the attack.

"The world has witnessed one sure and steadfast truth: Americans refuse to be terrorized," Obama said in his radio and Internet address released Saturday. "Ultimately, that's what we'll remember from this week. That's what will remain. Stories of heroism and kindness, resolve and resilience, generosity and love."

"Amazing Americans"

In the Republican address, Sen. Tim Scott of South Carolina praised the first responders who ran toward danger and sacrificed their own safety to assist victims.

"These amazing Americans, some of whom charged through fences and barricades, put their own lives on the line to help others," Scott said.

"We are so thankful for these women and men, who on a daily basis sacrifice for our nation -- they are our friends, our family, our neighbors," he says.

He also acknowledged the sadness of the week's events. "The Boston Marathon bombing has left us all with a heavy heart and we pray for the victims and their families," he says.  But he vowed that when it comes to terrorism on American soil, there is no corner on Earth, no hiding place in America that will keep us from finding you," he says, adding later, "Our freedom is our most precious possession -- any effort to take it away will only strengthen our determination."

Both addresses were recorded before Friday evening's tension-filled capture of the teenaged suspect.

In his remarks after the younger Tsarnaev brother was taken into custody, Obama called him and his bother "terrorists" and said his capture "closed an important chapter in this tragedy."

Still he added: "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 to stand, walk and live again deserve answers," he added.

The president also acknowledged the fertilizer plant disaster in West Texas, which he describe as a "tightknit community in Texas devastated by a terrible explosion.""I want them to know that they are not forgotten," he said, pledging to provide resources to recover and rebuild.

The Associated Press contributed to this story