President Obama delivered uplifting words to end an interfaith memorial service in Boston to honor the victims of the bombings at the finish line of the Boston Marathon.

President Obama addresses Boston Marathon interfaith service (WCVB TV)

President Barack Obama told the gathered at the Cathedral of the Holy Cross in Boston's South End,  "there is a piece of Boston in me" as he paid tribute to the city shaken by what he has called an act of terror. "Every one of us stands with you," he said, declaring later: "You will run again!"

He also vowed that whoever planted the bombs will be found. "Yes, you will face justice. We will find you. We will hold you accountable, but, more than that, our fidelity to our way of life, to a free and open society, will only grow stronger, for God has not given us a spirit of fear and timidity but one of power and love and self discipline," said Obama.

The President left the church and will visit with Boston Athletic Association volunteers. He will also visit patients at Mass General Hospital while Michele Obama will go to Children's Hospital.

Boston Mayor Tom Menino addresses service (WCVB TV)

An emotional Mayor Tom Menino said he had "never been prouder" of his city for the way it has handled the bombing. He also mentioned Yankee Stadium's playing of "Sweet Caroline" at Tuesday's game and cited each victim. Menino stood behind the alter; he has been confined to a wheelchair since having leg surgery.  "Nothing can defeat the heart of the city."

People began lined up outside the church at  5 a.m. to get into the service in an attempt to start the healing process even as investigators continue to look for a suspect in the bombing that left 176 injured and 3 dead.

Yo Yo Ma serenaded people as they arrived including former Massachusetts Governors Mitt Romney, William Weld and Mike Dukakis as well as most of the Massachusetts Congressional delegation.

2 Men Are Not Suspects

Homeland Security Secretary Janet Napolitano testifies during a House Homeland Security Committee hearing (Mark Wilson/Getty Images)

The investigation into the bombing goes on as Homeland Security Secretary Janet Napolitano today said the FBI wants to speak with two men seen in at least one video from the Boston Marathon, but she says she isn't calling them suspects.

Without providing details of the men's appearance or what the video shows, Napolitano told the House Homeland Security Committee on Thursday that "there is some video that raised the question" of two men the FBI would like to interview but said she wouldn't described them as suspects.

Napolitano said it's still unclear whether the bombs that exploded near the finish line of the Boston Marathon were the work of foreign or domestic terrorists. She said the investigation is continuing "apace."

The FBI wants to talk to two men who are caught in pictures near the finish line just before the blasts with back packs. Their pictures have been given to law enforcement but will not be shown to the public for fear of impeding the investigation according to CNN.

No media briefings were held yesterday by the FBI, which cancelled several planned sessions.

Resolution Will Not "Happen By Magic"

Massachusetts Gov. Deval Patrick (D) said he shared the frustration that the person or people responsible were still at large, but he said solving the case will not "happen by magic."

"It's going to happen by doing the careful work that must be done in a thorough investigation," Patrick said. "That means going through the couple of blocks at the blast scene square inch by square inch and picking up pieces of evidence and following those trails, and that's going to take some time."

Victims Continue To Recover

Cellist Yo Yo Ma and quartet practice for interfaith service (Twitter)

At least 14 bombing victims, including three children, remained in critical condition. Dozens of victims have been released from hospitals, and officials at three hospitals that treated some of the most seriously injured said they expected all their remaining patients to survive. A 2-year-old boy with a head injury was improving and might go home Thursday, Boston Children's Hospital said.

On Wednesday, investigators in white jumpsuits fanned out across the streets, rooftops and awnings around the blast site in search of clues. They picked through trash cans, plastic cup sleeves and discarded sports drink dispensers.

Boston Strong At The Garden

Jim Rogash/Getty Images

The Boston Bruins honored the victims of the bombing with a moving rendition of the Star Spangled Banner sung by the crowd. Rene Rancourt, who has sang the anthem for the past 30 years came to center ice at Boston Garden dressed in his trademark tuxedo and gold bow tie. He sang the first few lines then gestured to the crowd to join in. Most of the 17,565 fans lifted their voices in an a cappella version.

After the game, members of the Bruins and the Buffalo Sabres gathered at center ice and hoisted their sticks in recognition of the fans, the city and the determination of both to remain resilient

The Associated Press contributed to this story