BOSTON -- The anniversary of the Boston Marathon bombings was marked with a solemn wreath-laying ceremony Tuesday morning, the first tribute in a day dedicated to honoring the three people who died, the more than 260 people who were injured and those who rushed to help them.
The ceremony at the site of the twin explosions was attended by the families of the bombing victims - Martin Richard, Krystle Campbell and Lu Lingzi - as well as relatives of Massachusetts Institute of Technology police Officer Sean Collier, who was killed in the aftermath of the blasts.
Gov. Deval Patrick, Mayor Martin J. Walsh and Boston Cardinal Sean O'Malley were among those who attended the ceremony held in a light rain as bagpipes played. O'Malley offered a prayer.
In Washington, President Barack Obama planned to observe the anniversary with a private moment of silence at the White House.
"Today, we recognize the incredible courage and leadership of so many Bostonians in the wake of unspeakable tragedy," Obama said in a statement. "And we offer our deepest gratitude to the courageous firefighters, police officers, medical professionals, runners and spectators who, in an instant, displayed the spirit Boston was built on - perseverance, freedom and love."
Obama said this year's race, scheduled for Monday, will "show the world the meaning of Boston Strong as a city chooses to run again."
Vice President Joe Biden, Patrick and former Mayor Tom Menino were among the dignitaries expected to honor the victims later Tuesday during an invitation-only tribute at the Hynes Convention Center, which about 2,500 people were expected to attend. Several survivors also were scheduled to speak, including newlywed Patrick Downes and dancer Adrianne Haslet-Davis, both of whom lost their lower left legs in the bombings.
Carlos Arredondo, the cowboy hat-wearing spectator who was hailed as a hero for helping the wounded after the bombings, said he came to the tribute ceremony to support survivors and their families.
"You can see how the whole community gathered together to support them and remember," he told reporters before the program began.
Boston police Commissioner Williams Evans said the anniversary is an emotional day and brings back "some terrible memories."
"Hopefully, today brings the city and the families some sense of comfort and some healing," Evans said before ceremonies began.
Dr. Lyle Micheli has been medical coordinator at the marathon finish line since 1975.
"I want to pay tribute to people who were killed," he said.
He said medical personnel at last year's marathon were unprepared to treat the kind of traumatic injuries they saw after the bombings. This year, they have been equipped with "trauma kits" purchased from the Israeli army. The kits contain tourniquets, sterile dressings and compressor dressings.
Between 2:30 p.m. and 3 p.m., a flag-raising ceremony and moment of silence will be held at the marathon finish line, to mark the time and place where two bombs exploded on April 15, 2013.
Authorities say two brothers planned and orchestrated the attack and later shot and killed Collier during an attempt to steal his gun. Tamerlan Tsarnaev, 26, died following a shootout with police several days after the bombings. Dzhokhar Tsarnaev, 20, has pleaded not guilty to 30 federal charges and is awaiting trial. He faces the possibility of the death penalty.
The Tsarnaevs, ethnic Chechens who lived in the former Soviet republic of Kyrgyzstan and the Dagestan region of Russia, settled in Cambridge, outside Boston, more than a decade ago after moving to the U.S. as children with their family.
Prosecutors have said Dzhokhar Tsarnaev left a hand-scrawled confession condemning U.S. actions in Muslim countries on the inside wall of a boat he was found hiding in following the police shootout.