Don't rush to judgment in Boston case, Obama urges

But he acknowledged that many unanswered questions remain about the motivations of the two men accused of perpetrating the attacks that unnerved the nation.

"The families of those killed so senselessly deserve answers," said Obama, who branded the suspects "terrorists."

The president spoke from the White House briefing room after 7 p.m. Tucson time, just more than an hour after law enforcement officials apprehended 19-year-old Dzhokhar Tsarnaev. The capture of the second suspect capped a frenzied week in Boston, Washington and elsewhere around the country.

Letters addressed to Obama and Sen. Roger Wicker, R-Miss., were found to contain traces of poisonous ricin in tests, evoking eerie parallels to the anthrax attacks that followed the terror attacks of Sept. 11, 2001. And a massive explosion leveled a Texas fertilizer plant, leaving at least 14 people dead and more than 200 injured.

In his remarks Friday, Obama told the people of West, Texas, that "they are not forgotten."

But he focused his remarks on the day's events in Massachusetts, saying the nation owed a debt of gratitude to law enforcement officials and the city of Boston, which was paralyzed Friday by the manhunt.

The president's praise for law enforcement was echoed by Republican leaders on Capitol Hill.

House Speaker John Boehner of Ohio called their actions "a job well done under trying circumstances," while Senate Minority Leader Mitch McConnell of Kentucky said the nation "marveled at the coordination, skill and bravery of military, intelligence and law enforcement officials at every level."

Obama urged the public against rushing to judgment as officials seek answers to the many questions that remain.

"When a tragedy like this happens, with public safety at risk and the stakes so high, it's important that we do this right," he said. "That's why we take care not to rush to judgment."