Two Dorchester residents light candles during a candlelight vigil for the one-year anniversary of the Boston Marathon bombings at Garvey Park on Tuesday in Boston, Massachusetts. Two pressure cooker bombs killed three and injured an estimated 264 others during the Boston marathon, on April 15, 2013. Photo: AFP

US Vice President Joe Biden, local leaders and officials and survivors of the Boston Marathon bombing shared messages of thanks and defiance on Tuesday at a tribute to the three people killed and 264 wounded in the attack exactly one year ago.

From Patrick Downes, who lost a leg when a pair of homemade bombs ripped through the crowd at the race's finish line, to Biden, speakers recalled how police officers, spectators and others on the scene reacted immediately to help the wounded amid the chaos on April 15, 2013.

Former Boston mayor Thomas Menino, who managed the response to the attack during the final year of his two decades in office, recalled the struggles of the families of Martin Richard, 8, Krystle Campbell, 29, and Chinese national Lu Lingzi, 23, who died in the largest mass-casualty attack on US soil since September 11, 2001.

"You have struggled to get through the good days and the bad," said Menino, who had been hospitalized at the time of the blasts but responded to the scene against his doctor's orders.

"I know because so many of you have told me about this year of firsts. First birthday without your beloved son, first holiday without your daughter, first July 4 where the fireworks scared you."

Police detonated two backpacks Tuesday night and arrested a suspect on the anniversary of last year's deadly bombings, media reported.

Hundreds of people were evacuated after the backpacks were found at the scene of the twin bombings that killed three people exactly a year ago.

The Boston Police Department wrote on its official Twitter account that a male suspect had been taken into custody in connection with the unattended backpacks.

Later, the backpacks were detonated as a precautionary measure, said Boston police Superintendent Randall Halstead.

The suspect, identified as Kevin Edson, 25, was walking barefoot down the middle of Boylston Street just before 7 pm, the Boston Globe reported.

Halstead said the man was dressed in black, carrying a knapsack and acting strangely but he did not give details of his behavior.

Edson told an officer that he had a rice cooker in the bag, at which time he was arrested and the bomb squad was called in, said Halstead.

AFP