The street sweepers couldn’t get past the police tape. So when night fell on the streets around the Boston Marathon’s finish line, the messy aftermath of a big race was still sitting where runners had left it. Piles of discarded silvery “space blankets.” Sneaker-smashed banana peels.

And, at one marathon information booth, a sheet full of unanswered questions.

The sheet was marked “Runner/Family relations triage.” On it, some marathon staffer had taken down information from family members, who were looking for runners they couldn’t find.

“Runner disposition?” the sheet asked. The sheet didn’t have answers.

Instead, the booth was abandoned, and the sheet had been left on top of a nearby garbage can, incomplete.

Monday night should have been packed in Boston’s Back Bay neighborhood, as exhilirated runners celebrated in the area’s upscale bars and restaurants. Instead, it was a crime scene, barricaded off, and left as it was. There was a policewoman with an assault rifle in front of the Taj Hotel, and a group of National Guardsmen manning a checkpoint in front of Restoration Hardware.

“We thought it was the bleachers that had collapsed,” when the blasts reverberated through the neighborhood, said Tina Tran, 30, a transplant from Fairfax, Va., who lived a block from one of the blasts. She had gone downstairs to find a stranger in the building’s lobby, who was bleeding but wasn’t sure where it was coming from.

“She didn’t even know where the cuts were, herself,” said Long Cao, 35, Tran’s companion. They had left her and evacuated. At nightfall, they were still out, sitting on a sidewalk looking at the news crews broadcasting from the edge of the closed-off neighborhood.

“We probably need to look for a hotel,” Tran told him. She had only taken her phone with her, nothing else.

“Anderson Cooper’s here,” Cao said. “Wow!”

Back Bay runs roughly five blocks north to south, and nine blocks east to west. But it contains some of Boston’s most sought-after residential blocks, as well as busy commercial blocks. It is no accident that the finish line is in Back Bay.

The one-way marathon course is drawn up a like an arrow into the heart of the city, starting in the outer outer suburb of Hopkinton. And ending right here, in front of the Boston Public Library.

On Monday night, the whole place was silent, and occupied.

People stopped at the head of Newbury Street, the main commercial thoroughfare, and took pictures of the empty blocks behind the police barricades.

At one checkpoint, 18 year-old Boston University student Bram Peterson rushed up to the Boston cops, riding his bike. “What’s the fastest way to the Mass. General?” he asked.

Peterson was in a rush to give blood.

“It’s like, ugghhh. Just [expletive],” he said, trying to explain his urgency. “My heart goes out.” Peterson isn’t from Boston, but he said he understood what this day means in this place, a triple celebration of the things Boston has and nobody else does.

That’s the Red Sox, who play a special early game so fans can watch the marathon finish. That’s the American Revolution, whose beginnings are commemorated on this Monday, Patriots Day. And that’s the 117 year-old marathon.

“This is an awful thing to happen on such a day. This is — this the soul of Boston,” Peterson said. Marathon Monday, he meant. “The soul of Boston.” He biked away, on a course to skirt the police lines toward the Massachusetts General Hospital.

A few blocks away, the Mass. Ave Tavern was full of locals, drinking because they weren’t allowed to go home. The televisions above the bar were showing the news coverage, the same footage of explosions and injured people. Somehow, it had all happened just a few blocks away, in front of the Marathon Sports store.

Then the grim footage stopped. President Obama came on.

He spoke about “the free and fiercely independent spirit [in] this great American city of Boston.”

The bar erupted.

“I just heard him say, ‘Boston,’ and everybody started applauding” said Alexandra Breshinski, a bartender.

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