AS HE wandered on to Boylston Street to greet his father with a toothy smile and a hug at the finish line of the Boston marathon, Martin Richard was the picture of childish joy.
Moments later, however, this bright and cheerful eight-year-old, who loved playing football and riding his bicycle, was dead -- killed by a flash of violence that shattered his family and left a city grieving.
A pressure cooker, packed with explosives and ball bearings, and stuffed into a black duffel bag, blew up on the pavement to which Martin had returned along with his mother Denise, sister Jane, and brother Henry.
As Bill Richard passed the finish line yards away, the explosion claimed his son's life, tore off one of five-year-old Jane's legs and delivered a blow to the head that gave Mrs Richard (43) serious brain injuries.
Within 12 seconds, a second duffel bag exploded further down the road, tearing into another section of pavement packed with crowds celebrating the race on Patriots' Day, a public holiday in Massachusetts.
No person or group has yet claimed responsibility for the atrocity which killed three people and injured 176, and authorities have been unable to establish a motive.
Mr Richard, a 42-year-old neighbourhood activist, spoke of his heartbreak yesterday as he lamented the loss of his "dear son".
"We thank our family and friends, those we know and those we have never met, for their thoughts and prayers," he said in a statement.
"I ask that you continue to pray for my family as we remember Martin."
The Richard family were proud of their Irish links, and had visited relatives in Co Kerry while Jane was growing up to be a talented Irish dancer. A second victim of the blasts, named last night as Krystle Campbell (29), also had Irish heritage.
A candle was burning last night outside the Richards' home on a quiet street in an affluent suburb of Boston, where a single word had been chalked on to the path by a neighbour: "Peace."
The same slogan was carefully written on a colourful poster drawn by Martin last year in a class at Neighbourhood House charter school.
"No more hurting people," he wrote across the top of the page.
"They are just the sweetest, greatest kids," said Holly Moulton, a teacher at the school, choking back tears after laying flowers at their door.
"Always so happy and full of life."
Of the victims, 17 were in a critical condition in hospital last night, severely wounded by shrapnel such as nails and ball bearings from the six-litre cookers. Medics said the bombs appeared to have been designed to cause maximum human carnage.
No other victims' names were released.
As investigators struggled to identify the bombers, US President Barack Obama described the attacks as "an act of terror" and promised that Americans would respond "selflessly, compassionately, unafraid".
Classes have been cancelled this week at Martin's school, where Mrs Richard, a neighbourhood watch official, worked as a librarian and read books to young pupils in a voice that "brought stories to life".
Residents of the family's neighbourhood, once home to president John F Kennedy's mother, Rose, gazed into the distance yesterday from the doorsteps of Civil War-era homes.
Betty Delorey recalled Martin hopping over the fence outside his house and clambering up trees. Jane Sherman remembered the eight-year-old heading out to play baseball with the father he adored.
"What a beautiful smile he had," said Darren McNair (51), whose son, Tyler, played football with Martin.
"I will always remember seeing it from across the field. What a senseless, senseless tragedy."
The 26th and final mile of the marathon was dedicated to the 26 victims of December's Sandy Hook school shooting in Newtown, Connecticut.
Indeed, nine Newtown residents were running in honour of the victims, while some parents of the dead children watched from the VIP stands at the finish line. All escaped physical harm, but not the shock.
"Newtown cannot handle any more of this," said Lisa Abrams, whose husband was among the competitors.
For Bostonians, the disbelief was still strong. "It was like something that you see in a movie or on the news in another country. It's not something that you experience on Patriots' Day at the Boston Marathon," said Matt Hodgens, who as a child handed out orange slices to thirsty runners and was near the blast scene.
But Thomas Menino, the long-time mayor, vowed that a city renowned for its tough Irish and Italian roots would fight back.
Mr Menino (70) checked himself out of hospital where he was being treated for a broken leg, to address his fellow constituents from a wheelchair.
"Boston will overcome," he said.
By Jon Swaine in Boston