The officials told the AP that no gun was found in the boat. Boston police Commissioner Ed Davis said earlier that shots were fired from inside the boat.
Asked whether the suspect had a gun in the boat, Davis said, "I'm not going to talk about that."
Kurt Schwartz, director of the Massachusetts Emergency Management Agency, did respond to the report.
"Within half a mile of where this person was captured, a police officer was shot. And I know who shot him." Schwartz said. "And there were three bombs that went off, and I know where those bombs came from. ... To me, it does not change anything. This guy was captured alive and will survive. True or not true, it doesn't change anything for me."
The suspects' parents, Anzor Tsarnaev and Zubeidat Tsarnaeva, plan to fly to the U.S. from Russia on Thursday, the father was quoted as telling the Russian state news agency RIA Novosti. The family has said it wants to take Tamerlan's body back to Russia.
In Russia, U.S. investigators traveled to the predominantly Muslim province of Dagestan and were in contact with the brothers' parents, hoping to gain more information.
Investigators are looking into whether Tamerlan, who spent six months in Russia's turbulent Caucasus region in 2012, was influenced by the religious extremists who have waged an insurgency against Russian forces in the area for years. The brothers have roots in Dagestan and neighboring Chechnya but had lived in the U.S. for about a decade.
While in the U.S., the brothers received welfare benefits.
The Office of Health and Human Services in Massachusetts confirmed a Boston Herald report Wednesday that Tamerlan, his wife and daughter had received welfare benefits up until last year, when he became ineligible based on family income.
The state also says Tamerlan and his brother received welfare benefits as children through their parents while the family lived in Massachusetts.
Neither was receiving benefits at the time of the bombing.
At MIT, bagpipes wailed as students, faculty and staff members and throngs of law enforcement officials paid their respects to MIT police Officer Sean Collier, who was ambushed in his cruiser three days after the bombing.
Biden told the Collier family that no child should die before his or her parents, but that, in time, the grief will lose some of its sting.
"The moment will come when the memory of Sean is triggered and you know it's going to be OK," Biden said. "When the first instinct is to get a smile on your lips before a tear to your eye."
The vice president also sounded a defiant note.
"The purpose of terror is to instill fear," he said. "You saw none of it here in Boston. Boston, you sent a powerful message to the world."
In another milestone in Boston's recovery, the area around the marathon finish line was reopened to the public, with fresh cement still drying on the repaired sidewalk. Delivery trucks made their way down Boylston Street under a heavy police presence, though some damaged stores were still closed.
"I don't think there's going to be a sense of normalcy for a while," Tom Champoux, who works nearby, said as he pointed to the boarded-up windows. "There are scars here that will be with us for a long time."
Jakes and Dozier reported from Washington. Associated Press writers David Crary, Bridget Murphy and Bob Salsberg in Boston, Lynn Berry in Moscow and Matt Apuzzo, Adam Goldman, Eric Tucker, Pete Yost and Eileen Sullivan in Washington contributed to this report.