US remembers Boston victims

The president was at Boston's Roman Catholic Cathedral of the Holy Cross on Thursday to take part in an interfaith service to commemorate victims of the bombing. Three people were killed, with some 170 others left injured, many losing limbs.

Having paid tribute to those who had died, Obama told the congregation that Boston's spirit as a city would help it to recover.

"You will run again because that's what the people of Boston are made of," said the president. "Your resolve is the greatest rebuke to whoever committed this heinous act," Obama said, warning that justice would be meted out to those involved in the attack.

"We will find you and we will hold you accountable," he said. Obama added that America would not bow to those who threatened a "free and open society."

"We may be momentarily knocked off our feet, but we'll pick ourselves up and well keep going. We'll finish the race," Obama said.

Boston Mayor Tom Menino, appearing in a wheelchair after breaking a bone in his leg at the weekend, also spoke at the service about the city's response to a "hateful act."

"Nothing can take us down because we take care of one another," said Menino.

"It's a glorious thing the love and strength that covers our city," said the mayor. "This is Boston; a city with courage, compassion and strength that knows know bounds," he added.

The city's Cardinal Sean O'Malley addressed the congregation, as well as members of the Jewish, Muslim and Greek Orthodox faiths and several Protestant denominations.

Local officials including Massachusetts Governor Deval Patrick and Congressman Ed Markey, who also attended the event, were among those who welcomed Obama as he arrived on Air Force One at Boston Logan International Airport.

Hunt goes on 'apace'

As the commemoration took place, the search went on for the perpetrators of Monday's bombing. Homeland Security Secretary Janet Napolitano announced that the investigation was continuing "apace" and that the FBI was eager to speak to two men.

"We have been collecting video from a variety of sources," Napolitano told a Congress hearing. "There is some video that has raised the question of those that the FBI would like to speak with. I wouldn't characterize them as suspects under the technical term, but we do need the public's help in locating these individuals."

The crudely-fashioned bombs were said to have been made with ordinary kitchen pressure cookers, explosives, nails and ball bearings.

The blasts killed 8-year-old Martin Richard, from Boston, 29-year-old Krystle Campbell, from nearby Medford, and Lu Lingzi, a graduate student from China who was attending Boston University.

rc/jr (AFP, AP, dpa)