Two of the three people killed in the bombings at the Boston Marathon have been identified as eight-year-old Martin Richard and 29-year-old Krystle Campbell.
They are two of the three people killed in Monday's explosions near to the race's finishing line. Officials have said more than 170 people had also been injured in the attack.
Martin was at the race with his mother and sister to watch his father take part in the race. His mother and sister were seriously injured in the blasts and remain in hospital. Today his father Bill paid tribute to him:
– Martin Richard's father Bill
My dear son Martin has died from injuries sustained in the attack on Boston.
My wife and daughter are both recovering from serious injuries.
We thank our family and friends, those we know and those we have never met, for their thoughts and prayers.
I ask that you continue to pray for my family as we remember Martin.
We also ask for your patience and for privacy as we work to simultaneously grieve and recover. Thank you.
International Editor Bill Neeley reports on the investigation into the explosions:
Audio recordings of the emergency services' response to the bombings just seconds after the attack have been released:
Krystle Campbell was the second victim of the Boston bombings to be named. The 29-year-old was a restaurant manager from nearby Arlington, Massachusetts.
Speaking to local media, her father described her as a "wonderful, wonderful girl".
It says officials at first thought Krystle had survived the blasts and that Karen had died after she was found carrying Krystle's ID.
The report says Krystle's parents were ushered into a hospital room where they found Karen lying seriously injured.
They then reported their daughter missing and later found she was among the dead.
Her family later said in a statement they were "heartbroken" by her death:
Washington Correspondent Robert Moore reports on the bombings that stunned Boston:
Today US President Barack Obama said the American people refuse to be terrorised following the events in Boston, branding the bombings as a "heinous and cowardly act".
In a news conference at The White House, he said: "The American people refuse to be terrorised because what the world saw yesterday in the aftermath of the explosions were stories of heroism and kindness and generosity and love...So if you want to know who we are, what America is and how we respond to evil - that's it. Selflessly, compassionately, unafraid."
Watch Obama's speech in full:
The leading FBI official investigating the Boston Marathon explosions - Rick Deslauriers - said today that pieces of black nylon, possibly from a backpack, and fragments of BBs and nails have been found at the scene of the explosions.
He added that the FBI had received more than 2,000 tips from the public but no individual or group had claimed responsibility for the atrocity.
Speaking at a press conference, he also appealed to the public for information, saying: "Someone knows who did this."
ITV News presenter Mark Austin spoke to one of the runners who witnessed the bombings: