JEFFREY BROWN: And as the investigation continues, so too the mourning.
As we heard, President Obama came to Boston today to attend a memorial service for victims of the bombing.
Hundreds lined up before dawn this morning, hoping to secure one of the 2,000 seats in Boston's Roman Catholic Cathedral of the Holy Cross. Tight security blanketed the area and many were turned away.
SHELLY SMITH, Boston: We have to live. We have to go on with our lives. We don't know why things happen. And it could have been any one of us. I know we just pray and we stay strong with each other.
MICHAEL GOOLKASIAN, Boston: It's different. When I see stories, I really -- I get really sad, really sad. And it bothers me on so many different levels. But Boston will -- Boston is tough. Man, this city is the rocks. We will get through it.
JEFFREY BROWN: Inside, prominent politicians, including Massachusetts Senators Elizabeth Warren and Mo Cowan, and former Governor and presidential candidate Mitt Romney, joined in honoring the bombing victims.
Mayor Thomas Menino, who missed attending the marathon because of a broken leg, praised his city for its strength in the face of the tragedy.
MAYOR THOMAS MENINO, D-Boston: Nothing can defeat the heart of this city, nothing. Nothing will take us down, because we take care of one another. Even with the smell of the smoke in air and blood on the streets, tears in our eyes, we triumphed over that hateful act on Monday afternoon, because this is Boston, a city with courage, compassion, the strength that knows no bounds.
JEFFREY BROWN: Six religious leaders spoke.
Rev. Nancy Taylor of Boston's Old South Church, located near the race's finish line, recounted the sacrifice she witnessed Monday.
REV. NANCY TAYLOR, Old South Church: And from the church's tower, this is what I saw that day. I saw people run toward, not away, toward the explosions, toward the chaos, the mayhem, toward the danger, making of their own bodies sacraments of mercy.
JEFFREY BROWN: Cellist Yo-Yo Ma accompanied the Boston Children's Chorus.
And Gov. Deval Patrick linked the state holiday on Monday to American values.
GOV. DEVAL PATRICK, D-Mass.: How very strange that the cowardice unleashed on us should come on marathon day, on Patriots' Day. An attack on our civil ritual, like the marathon, especially on Patriots' Day, is an attack on those values.
And just as we cannot permit darkness and hate to triumph over our spiritual faith, so we must not permit darkness and hate to triumph over our civic faith. That cannot happen, and it will not.
JEFFREY BROWN: Before the service, President Obama met with the family of Krystle Campbell, one of three killed. And in addressing the gathering, he sought to comfort the unnerved city.
PRESIDENT BARACK OBAMA: Because, after all, it's our beloved city, too. Boston may be your hometown, but we claim it, too.
Your resolve is the greatest rebuke to whoever committed this heinous act. If they sought to intimidate us, to terrorize us, to shake us from those values that make us who we are as Americans, well, it should be pretty clear by now that they picked the wrong city to do it.
Not here in Boston. Not here in Boston.
And that's what you have taught us Boston. That's what you have reminded us, to push on, to persevere, to not grow weary, to not get faint. Even when it hurts, even when our heart aches, we summon the strength that maybe we didn't even know we had, and we carry on, we finish the race.
JEFFREY BROWN: Later, President Obama spoke with members of the Boston Athletic Association at a nearby high school and visited with victims and staff at Massachusetts General Hospital.