A photo of a Boston Marathon bombing victim lying on his back has become one of the most enduring images of the disaster after it was revealed he climbed back to his feet and finished the race.
Retired builder Bill Iffrig, 78, is seen in shocking footage being knocked to the ground by the force of the first explosion just metres from the finish line.
But the triple-Boston Marathon veteran was helped back to his feet by a race official before he turned around and finished the race.
"I got down to within 15 feet of the finishing apron and just tremendous explosion, sounded like a bomb went off right next to me," Mr Iffrig told CNN.
"The shock waves just hit my whole body and my legs just started jittering around.
"I knew I was going down and so I ended up down on the blacktop."
He suffered just a scrape on the knee despite his proximity to the first of two bombs.
"Somebody came by with a wheelchair but I said, 'I'm fine.' I wanted to finish," he told the Seattle Times.
"First thing (when) I got up, I said, 'There's the line up there, I can get that far'."
The twin blasts killed three people and injured more than 140 more, with 15 people in a critical condition.
A boy confirmed killed in the blast has been named as Martin Richard, an eight-year-old from the southern Boston suburb of Dorchester.
His mother and sister suffered grievous injuries in the explosion, the Boston Globe reports.
The bombs were packed with ball bearings, contributing to a number of spectators losing limbs in the blast.
No-one has yet claimed credit for the act of terrorism.
Author: Nick Pearson. Approving editor: Fiona Willan.