Noah Pozner and Jack Pinto, both aged six, who were killed at Sandy Hook Elementary in Newtown, Connecticut, USA, were buried in tiny coffins as the rest of the nation anxiously sent children back to school amid tightened security.
Noah's life was remembered at a funeral home in Fairfield. A teddy bear and bouquet of white flowers lay at the base of an oak tree outside the service packed with mourners.
In a newspaper obituary, his parents, Lenny and Veronique Pozner, and four siblings said: "He was the light of our family, a little soul devoid of spite and meanness."
Noah was laid to rest at the B'Nai Israel Cemetery in the nearby town of Monroe.
The funeral of Jack Pinto was held at Newtown Village Cemetery.
A New York Giants American football fan, Jack was wearing a jersey with player Victor Cruz's number 80 as he lay in an open white casket at the service.
During Sunday's game, Cruz wore shoes with "RIP Jack Pinto" written on the side.
"Jack was an incredibly loving and vivacious young boy, appreciated by all who knew him for his lively and giving spirit and steely determination," his parents, Dean and Tricia Pinto, and brother said in his newspaper obituary.
The funerals come a day after President Barack Obama visited Newtown. He said: "We can't tolerate this any more. These tragedies must end and to end them we must change."
Mr Obama's remarks were welcomed by relatives of teacher Victoria Soto, 27, who was killed as she tried to protect her first-grade students.
Her brother, Carlos Soto, said: "He made us feel like she really was a hero and that everyone should know it."
Noah was the youngest victim of the rampage but his twin sister, Arielle, escaped unhurt. The family's rabbi has said he encouraged Noah's mother to focus on her other four children amid the grief.
Pupils at Sandy Hook Elementary now attend classes in an empty school in a neighbouring town. Resident Tim Northrop said: "We have to go back into that building at some point. That's how you heal."
A more detailed picture of Adam Lanza's attack has now emerged. After killing his mother at home in her bed, Lanza shot his way into the school, which he attended as a child.
Police said Lanza was armed with hundreds of bullets in high-capacity magazines of about 30 rounds each for the Bushmaster AR 15 rifle and two handguns he carried into the school, and had a fourth weapon, a shotgun, in his car outside. He killed himself in the school.
In Washington, a pro-gun lawmaker called on Congress and the gun industry to come together on a "sensible, reasonable approach" to curbing high-powered, assault weapons.
Senator Joe Manchin, a West Virginia Democrat, said: "Never before have we seen our babies slaughtered. This has changed where we go from here."
New York City Mayor Michael Bloomberg, a persistent and vocal voice for gun control, warned Mr Obama against inaction.
The White House has said that gun control is part of the answer, but not the full solution, in briefings.