Boston paid solemn tribute Tuesday to the victims and survivors of the marathon bombings that traumatized the northeastern US city and stunned the nation one year ago.

Three people were killed and more than 260 others wounded when two pressure cooker bombs detonated near the finish line of the city’s famous marathon on April 15, 2013.

The attacks were allegedly carried out by two brothers of Chechen descent who had lived in the United States for years.

Vice President Joe Biden attended a tribute at the Hynes Convention Center just steps from the scene of the attack in the heart of the city of nearly one million.

Songs and orchestral music were interspersed with speeches and thanks to emergency workers and memories of the dead.

Former mayor Tom Menino, who was in office at the time of the attack, addressed the heartache of those who lost loved ones and people’s struggle to recover.

“This day will always be hard but this place will always be strong because we gather here today… to stand for the people in a city we love with all of our hearts,” Menino said at the ceremony.

There will be a moment of silence at 2:49 pm, the time when the first bomb exploded, and then church bells will toll across Boston.

In Washington, US President Barack Obama is to observe a moment of silence privately with aides in the Oval Office at about the same time.

Obama sent thoughts and prayers to those struggling to recover, and paid tribute to the “incredible courage and leadership of so many Bostonians in the wake of unspeakable tragedy.”

“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,” he said in a statement.

“One year later, we also stand in awe of the men and women who continue to inspire us — learning to stand, walk, dance and run again. With each new step our country is moved by the resilience of a community and a city.”

The two pressure-cooker bombs sent metal fragments flying through the crowd. Several of the wounded lost limbs.

This Monday, April 15, 2013 photo shows Tamerlan Tsarnaev, in blue baseball cap, and Dzhokhar A. Tsarnaev, in white baseball cap. This image was taken approximately 10-20 minutes before the Boston Marathon blast. (Photo credit: AP/Bob Leonard)

This Monday, April 15, 2013 photo shows Tamerlan Tsarnaev, in blue baseball cap, and Dzhokhar A. Tsarnaev, in white baseball cap. This image was taken approximately 10-20 minutes before the Boston Marathon blast. (Photo credit: AP/Bob Leonard)

Dzhokhar Tsarnaev, who is now 20, and his 26-year-old brother Tamerlan were identified thanks to pictures and video footage and eventually cornered by police after a four-day manhunt that paralyzed the city.

Tamerlan died after an exchange of fire with police, and Dzhokhar was wounded and captured. The younger Tsarnaev, a naturalized US citizen, will go on trial in November and could face the death penalty if convicted.

Biden, Massachusetts governor Deval Patrick and current Boston mayor Martin Walsh were also to speak at the tribute.

There will be a flag-raising ceremony and a moment of silence will be observed at the race’s finish line.

This year, the Boston Marathon — which has been run since 1897 — will take place on Monday, April 21.

Organizers have allowed thousands more runners to register — from about 27,000 in recent years to 36,000 this year, not far off the record 38,708 who entered in 1996 in the 100th marathon.

Security has been bolstered in the wake of the attacks, with more police on the streets, a “no-bag policy”, and glass bottles and large containers of any kind banned from the area.

The Tsarnaev brothers allegedly hid the explosive devices in backpacks.

Dzhokhar Tsarnaev has pleaded not guilty to 30 federal charges related to the bombings, including 17 serious charges that can carry sentences of death or life in prison.

The charges include using a weapon of mass destruction resulting in death, as well as conspiracy and bombing of a place of public use resulting in death, and carjacking.

Tsarnaev is also charged in connection with the fatal shooting of a campus police officer at the Massachusetts Institute of Technology during the brothers’ wild getaway attempt.