WASHINGTON (AP) -- President Barack 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.
"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.
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."
His remarks came a few hours after Obama spoke to Russian President Vladimir Putin to thank him for what the White House described as close cooperation on counter-terrorism, "including in the wake of the Boston attack." Putin expressed condolences for the victims in Boston.
In his comments to reporters late Friday Obama cautioned against a rush to judgment about the motivations of the suspects and "certainly not about entire groups of people."
"That's why we have investigations, that's why we relentlessly gather the facts, that's why we have courts," he said.
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."