Keri Palazzo knelt where the first bomb had exploded and thought of her father, killed on September 11. He was watching over her, she said, at the Boston Marathon finish line two years ago when the shock of the blast thumped through her chest and shattered her sunglasses but left her unharmed.
Blocks down Boylston Street, the family of Martin Richard stood silently as bagpipes skirled and two bright banners emblazoned with hearts were unfurled above the spot where the 8-year-old was killed in the second explosion.
At Saint Brendan School in Dorchester, more than 200 students watched four white balloons float into the clear blue sky, one for each of the people killed by the Tsarnaev brothers. One child murmured, “Are they going up to God?”
In gestures large and small Wednesday, Boston marked the two-year anniversary of the terror attacks that shocked the nation and brought the region to a standstill as officials hunted for the culprits.
Martin Richard of Dorchester was the youngest victim; 29-year-old Krystle Campbell of Medford and 23-year-old Lingzi Lu, a Boston University graduate student from China, were also killed in the explosions. About 260 people were injured. Several days later, MIT Police Officer Sean Collier was shot to death by the bombers.
For the past two years, the Rev. Nancy Taylor said during a “Service of Resiliency” at Old South Church, Bostonians have been in “a kind of intimate dance, a slow dance, but one in which we have held on to each other and refused to let each other go.”
Her message to mark the day: “Keep dancing. Because for two years now, we have been written on each other’s dance cards, and there’s no way of getting out of it. We are each other’s destiny.”
At 2:49 p.m., the moment the first bomb exploded, the city fell silent, save for the sound of bells.
On City Hall Plaza, Mayor Martin J. Walsh stood with the Richard family. The father, Bill, clutched his 9-year-old daughter Jane, who lost a leg in one of the blasts. Her mother, Denise, kissed her head as older son Henry stood nearby.
The silence stretched from one moment into two, interrupted only by the chirp of birds and the rustle of a fluttering American flag. Finally, the Rev. Sean Connor stepped forward.
“I ask the Lord to watch over us, protect us, help us always be instruments of his peace,” Connor said. “May the Lord bless you and keep you and may his face shine upon you.”
The day of commemoration began in the morning chill, with two simple ceremonies on Boylston Street attended by the Richard and Campbell families as well as Walsh and Governor Charlie Baker, where the banners were unfurled.
The crowd at each was full of bombing survivors, many wearing blue and yellow clothing, with white pins marking One Boston Day, which Walsh declared as an annual day of kind acts and remembrance.
“This is a place where so much was lost, but it’s also a place where people are giving back,” Melissa Southwell, 37, said as she stood in her Marathon jacket beneath the banners at the first explosion site, her face wet with tears. “We need to have joy here. We need to have strength here.”
Two years ago, Southwell was watching the Marathon near the finish line when the first blast hit. Amid the chaos, she scooped up a little boy and took off in the opposite direction. Then the second bomb exploded, trapping her between two horrifying scenes.
“I just needed to be here today,” she said. Before the banners were unfurled, she ran down Boylston and planted her feet on the finish line.
After the ceremonies, Jeff Bauman, who lost most of both legs, put his arm around Carlos Arredondo, who had rushed to his aid after the blast.
“I’m thankful that I’m here and that I got to live the rest of my life,” Bauman said.
Handmade blue-and-yellow peace signs were posted along Boylston. One read, “No more hurting people. #PEACE” — a reference to a sign held by Martin Richard in a school photo.
Both bombing sites drew pilgrims throughout the day. Palazzo, whose father was killed in the 9/11 attacks, left his Mass card at the base of a tree from which others had hung running shoes and left flowers and balloons.
“I feel like the only reason I’m alive is because of him . . . because of him watching out for me,” said Palazzo, 28, who lives in Boston. “I want to protect the city. I feel like leaving him here is better than any flower.”
In the spirit of “One Boston Day,” many residents performed random acts of kindness across the city.
For Jeff Hanulec, that meant giving blood at a Red Cross event in the Sheraton ballroom. For members of Walk Boston, a pedestrian advocacy group, it meant sprucing up crosswalks to make traveling by foot safer for those heading into work in the morning.
For Maureen and Steve Palladino, visiting the city from North Andover, it meant giving money to the homeless and thanking first responders.
For many, the day brought grief, but the kindness of strangers offered solace.
An anonymous card left at a blast site bore Martin Richard’s name, a tiny shining star, and a simple, stark epitaph:
“Love and despair in Boston.”
Steve Annear of the Globe staff contributed to this report. Evan Allen can be reached at email@example.com. Follow her on Twitter @evanmallen.