WASHINGTON - The Tsarnaev brothers were armed with at least three firearms and several improvised bombs - including a pressure-cooker explosive - during confrontations with police, an arsenal that will be traced to determine whether someone outside the U.S. helped the Boston bombing suspects, a law enforcement official said Saturday.
Meanwhile, some investigators said the Boston Marathon bombing did not appear to have been orchestrated by al-Qaida, several U.S. officials said Saturday.
The suspects, Tamerlan Tsarnaev, 26, and Dzhokhar Tsarnaev, 19, came to the U.S. from Russia about a decade ago as ethnic Chechen refugees and were granted asylum, law enforcement sources have said. Tamerlan, who was killed in a gun battle with police Thursday, was a legal permanent U.S. resident. Dzhokhar, captured Friday, became a citizen on Sept. 11, 2012.
"This guy is probably not a Chechen separatist . . . I suspect he wasn't recruited by al-Qaida," said one senior counter terrorism official regularly briefed on the investigation, referring to Tamerlan, who traveled to Russia last year.
Rep. Peter King, R-N.Y., chairman of the intelligence subcommittee of the House Homeland Security Committee, agreed. "I don't think this was directed from overseas, I don't think this was planned from overseas."
Tamerlan Tsarnaev appears to have embraced Islamic extremism, the law enforcement official said, though it's unclear to what extent that was a main trigger for the violence.
King said it was possible Tamerlan met with extremists or received some training during a six-month trip to Russia in 2012, which officials are investigating.
But, the senior official said, the emerging story of the Tsarnaev brothers more likely fits the profile of previous domestic terror attacks and a number of mass shooting events in recent history.
The Associated Press reported Saturday that Tamerlan Tsarnaev used to rant at a neighbor about Islam and the United States, and that his younger brother relished debating people on religion, "then crushing their beliefs with facts."
Tamerlan "swaggered" through the family home like a "man-of-the-house type," one visitor recalled, while Dzhokhar seemed "very respectful and very obedient" to his mother.
Whatever drove them to this, their uncle is certain that Dzhokhar was not the one pulling the strings.
"He's not been understanding anything. He's a 19-year-old boy," Ruslan Tsarni said of his brother's youngest child. "He's been absolutely wasted by his older brother. I mean, he used him. He used him for whatever he's done. For what we see they've done. OK?"
In confrontations with the brothers Thursday and Friday, police faced a heavy arsenal of weapons.
One firearm was recovered after the shootout with police Thursday night in Watertown, where some 200 rounds of ammunition were exchanged, said the law enforcement official, who spoke on condition of anonymity because the case is still evolving.
That gun battle followed the shooting of a Massachusetts Institute of Technology police officer on campus.
Two more firearms were recovered in the backyard boat where Dzhokhar was captured Friday, the official said, adding that the serial identification on at least one of them "was ground down" to obscure the numbers.
He said that authorities consider the older brother to be the leader of the duo. "The brother was the catalyst in this thing," he said. "The younger brother followed him."
During an interview with CNN Saturday, Watertown Police Chief Ed Deveau said that the Thursday gun battle erupted when one of his officers spotted the brothers in two different cars. As he called for backup, the brothers exited the vehicles and "unloaded on our officers," Deveau said. "He was under direct fire . . . He has to jam it in reverse and try to get himself a little distance."
"They had pipe bombs and explosives," Deveau said. "During the exchange, all of a sudden something gets thrown at police officers. We find out it was the exact bomb used in the marathon ... a pressure cooker."
Ultimately, only one of the six officers was injured in the firefight.
"I'm extremely proud of these officers," Deveau said. "It was talent, guts and glory."