The third person killed in the Boston Marathon has been named as 23-year-old Chinese national Lu Lingzi.
Ms Lu, a Boston University graduate student, was standing among a large group of spectators close to the finish line on Boylston Street when the first blast went off.
The mathematics and statistics student was with two of her friends at the time, watching runners finishing the marathon.
One of those friends, Zhou Danling, suffered serious injuries and fell into a coma shortly after the attack, but is now said to be in a stable condition at the Boston Medical Center.
Speaking about Ms Zhou, Robert Hill - the dean of Boston University’s Marsh Chapel - told BU Today: "She is doing well… She has her friends around her, and she will soon have family around her."
Ms Lu’s friends said the 23-year-old had come to the US because it was her “dream to get a better education”.
Tributes were today paid to the two other victims of the twin blasts - eight-year-old Martin Richard and 29-year-old restaurant manager Krystle Campbell.
The young boy’s mother Denise and six-year-old sister Jane both suffered serious injuries in the attacks.
Ms Campbell’s 56-year-old father William described his daughter as a “very caring, very loving person” who went to watch the race with her best friend, whose boyfriend was running.
At least 176 people were injured in the explosions, with 17 still critically ill. Among that 17 are a nine-year-old girl and a 10-year-old boy.
Today the first images of the two devices that caused the devastation were released.
One picture shows twisted pieces of a metal container, while another is of wires connected to a battery. A circuit board is seen in another.
The two bombs were designed to cause maximum damage, being made from pressure cookers filled with ball bearings.
Pictures of bloodied pieces of shrapnel and ball bearings found close to the scene of the explosions were also released.
Similar bombs have been used in Afghanistan, Pakistan and the Middle East, but security experts said the Boston devices could just as easily have been assembled by a domestic extremist.
The FBI added that: “pieces of black nylon which could be from a backpack” had also been found at the scene.
The Police Commissioner of Boston, Ed Davis, was pressed on whether enough had been done ahead of the race to protect runners.
He revealed the areas where the bombs went off had twice been swept, the second time just an hour before the winners crossed the line.
He said he was now confronting “the most complex crime scene we have dealt with in the history of our department”.
US President Barack Obama is visiting Boston today.