It is hoped that the verdict to execute the surviving Boston Marathon bomber Dzhokhar Tsarnaev will close a "painful chapter", a US congressman has said.
Joe Kennedy III, who represents Massachusetts' 4th Congressional District, said via his official Twitter account:
Nothing will give us back what was lost at the 2013 Boston Marathon, but may this verdict bring a painful chapter to its close.
A woman who saw two sons lose limbs in the Boston marathon bomb attack says Dzhokhar Tsarnaev "destroyed my boys' lives" and her own.
As Washington Correspondent Robert Moore reports, the trial has allowed survivors of the atrocity to see justice being done, though no-one is talking of closure.
A number of survivors of the Boston Marathon bombing have reacted on Twitter to the death sentence handed to Dzokhar Tsarnaev.
Sydney Corcoran, who suffered shrapnel wounds and nearly died from blood loss following the attack, tweeted that she and her mother - who was also near the finish line - would now "be able to move on".
My mother and I think that NOW he will go away and we will be able to move on. Justice. In his own words, "an eye for an eye".
Adrienne Haslet, a dancer who lost part of her leg in the blast, tweeted that she was "thrilled with the verdict".
Rebekah Gregory - another survivor who decided to amputate her leg after numerous operations linked to the attack - said she was "completely numb".
Completely numb... and waiting anxiously for the day this is really over. My heart and prayers are with my Boylston Street family. <3
Two women, Krystle Campbell and Lingzi Lu, died in the attack while Martin Richard, who was closest to the bomb, was just eight years old.Read the full story ›
The family of an eight-year-old boy killed in the Boston Marathon bombing had urged prosecutors not to press for the death penalty against Dzhokar Tsarnaev, one of the two brothers to have orchestrated the attack.
In an essay for the Boston Globe last month, Denise and Bill Richard wrote: "We are in favor of and would support the Department of Justice in taking the death penalty off the table in exchange for the defendant spending the rest of his life in prison without any possibility of release and waiving all of his rights to appeal."
"We know that the government has its reasons for seeking the death penalty, but the continued pursuit of that punishment could bring years of appeals and prolong reliving the most painful day of our lives," they wrote.
"We hope our two remaining children do not have to grow up with the lingering, painful reminder of what the defendant took from them, which years of appeals would undoubtedly bring."
Bill Richard had testified for the prosecution during the trial, in which Tsarnaev was convicted on numerous criminal counts.
He told the court how he had seen his son hit and killed by the explosion, which also damaged his wife's vision and injured his daughter Jane, now nine.
Boston Mayor Marty Walsh has said those who died in the Boston bombings will "forever be remembered and honoured".
In a statement, he thanked the jurors and judiciary for their service to the community and the country.
He added: "I hope this verdict provides a small amount of closure to the survivors, families and all impacted by the violent and tragic events of the 2013 Boston marathon.
"We will forever remember and honour those who lost their lives and were affected by those senseless acts of violence in our city.
"Today, more than ever, we know that Boston is a city of hope, strength and resilience that can overcome any challenge."
Members of the federal jury cried but Dzhokar Tsarnaev remained reactionless as the death sentence was read out in a federal court in Massachusets.
Tsarnaev - wearing a dark sport coat with a light-coloured shirt - had his head bowed slightly, with his hands folded in front of him.
Following the announcement, Judge George O'Toole described the jury as a "model for future juries".
"You have sat through a trial that has had horrible images and poignant testimony," he added.
Boston bomber Dzhokhar Tsarnaev has been sentenced to death but it could be many years before that actually happens.
ITV News Washington Correspondent Robert Moore said there will be many appeals before he is executed.
The appeal process, mandatory in this case, will last many years. If it fails, Tsarnaev will be put to death at federal facility in Indiana.
The jury in the trial of Dzhokhar Tsarnaev took 14 hours of deliberations to reach their decision to sentence the 21-year-old to death by lethal injection.
Tsarnaev was convicted last month of all 30 federal charges against him, 17 of which carried the possibility of the death penalty.
The bombing killed three people and injured more than 260 others.
Tsarnaev killed a Massachusetts Institute of Technology police officer days later.
The defence sought to save Tsarnaev's life by pinning most of the blame on his radicalised older brother.
But prosecutors portrayed Tsarnaev as an equal partner in the attack and so heartless he placed a bomb behind children, killing an eight-year-old boy.
In response to the sentencing to death of Dzhokar Tsarnaev, the US Attorney General said: "The ultimate penalty is a fitting punishment for this horrific crime."
Dzhokar Tsarnaev coldly and callously perpetrated a terrorist attack that injured hundreds of Americans and ultimately took the lives of three individuals: Krystle Marie Campbell, a 29-year-old native of Medford; Lingzi Lu, a 23-year-old Boston University graduate student from China; and Martin Richard, an 8-year-old boy from Dorchester who was watching the marathon with his family just a few feet from the second bomb.