Balls of newspaper flew around in the wind on Boston's Boylston Street on Tuesday amid angry mourning for the three dead and more than 140 injured from the twin bomb attack on the city's famed marathon.
The finish line of the world's oldest international marathon remained sealed off as police imposed tight security along the central street and around the city, closing one metro station and carrying out bag checks on trains and buses.
Police hunted for clues in Boylston Street which was still strewn with debris from the two bombs in the cold spring wind blowing through the city.
Some of the 27,000 race participants went as close as they could to the finish line to pay tribute. "I am leaving today but I had to come," said Lea Elliasson, 55, who came from Sweden to take part in the tragic 117th Boston marathon.
"I finished 15 minutes before the bombs so I know I am lucky," added the woman who was running to raise money for the disabled in her home town. Many other runners in bright blue Boston marathon jackets were also out.
Boston city authorities said that counselling would be available at schools and for marathon runners who felt they needed help after the blasts.
Boston mourned in particular the family of Martin Richard, an eight-year-old who was killed in the blast as he waited for his father to cross the finish line.
The boy's six-year-old sister lost a leg in the attack and his mother was also gravely injured, media quoted relatives as saying.
A candle was left on the steps of the family home in the Dorchester district and the word "peace" was scrawled in chalk on the sidewalk.
Other tragic stories emerged as doctors told how many of the wounded suffered from metal tacks and ball bearings in the bombs.
Liz Norden, a mother of five, told the Boston Globe how two of her sons had lost a leg in the blast. Both had gone to Boylston Street to see a friend finish the race.
"Ma I'm hurt real bad," Norden quoted one of her sons as telling her in an agonizing phone call from the ambulance taking the brothers to hospital.
Doctors said that many victims had legs blown off by the blast and some had to have amputations at the scene.
Police said the heightened security would last for several days. Many tourist landmarks were closed and sporting events such as the Boston Celtics basketball game against the Indiana Pacers on Tuesday was canceled because of the tragedy.