From Globe Correspondent Seth Lakso: Walking toward what was the finish line of the Boston Marathon just twenty minutes following the first two explosions, the streets were filled with racers and their families making their way away from Copley. Many of the people were in tears, or on their phones reassuring loved ones that they were safe.

The streets were completely empty and cordoned off surrounding Copley Plaza.

The medical tent was flanked by five ambulances facing down Huntington Ave. They loaded wounded two at a time, while medical personnel were unable to say for sure where the wounded were heading.

Inside the tent sections were cordoned off and labeled: “triage, triage II, and morgue.”

The section labeled morgue was blocked from view.

In the triage area closest to the ambulances, I could see half a dozen wounded runners. One woman had half her head wrapped in a bandage. Two others had large wraps over their legs.

“[There were] a lot of lower leg injuries,” said B.A.A. Head Nurse Jeanette Corsini. “Obviously some pretty horrific injuries.”

At least 25 patients were moved via ambulance by Corsini’s estimate. “I don’t know though because [the ambulances] were back and forth,” she said.

Corsini then commended the work of the medical staff and first responders.

“Everyone’s done a great job, obviously this was totally unexpected,” she said. “I think that people came together. Thank god Boston EMS was here. But I think everyone fell right into place and did what they needed to do. This isn’t something you prepare for.”

From Neil Swidey:

Kelly Beckett , 39, of Milton, and her sister Kristen Souza, 36, of North Attleboro, were running in honor of their mother, who was diagnosed with stage 4 cancer in August. Beckett had run before, but this was Souza’s first time. They had just reached Mile 20 when they were told by race officials to stop and turn out. The race was over.

They reversed direction, walking nearly a mile back into Newton Centre. “I can’t believe we’re walking backwards,” Souza said as they walked along Centre Street. Before turning off Commonwealth Avenue, they had passed a medical tent and grabbed BAA mylar blankets to wrap themselves in. “Grab one before they’re all gone,” Beckett told her sister, who had been training for her first marathon since October.

“Our family had finish line passes,” Beckett said. “Luckily, they were on their way and hadn’t made it there yet.” Souza’s phone had already died, but fortunately Beckett’s still had juice.

“It’s all so overwhelming,” Beckett said. “You assume there’s high security, but the course is so long that I guess it’s impossible to guard against everything.”

The sisters were heading to Starbucks to wait for a ride. They had just $5 between them, and were hoping the baristas would look kindly on them, until their family managed to get there.

A swarm of Newton police officers cordoned off the intersection of Commonwealth Avenue and Centre Street. The popular race viewing spot that had been three deep with spectators before the marathon had been stopped was now a desolate, windswept area. Captain Marc Gromada, who has worked the marathon for most of his nearly 25 years on the Newton force, was in charge of this year’s race for the department.

“We were told to shut down the race so we took precautions and made alternate routes to get the rest of the runners off the route,” he said.

After that, the precautions continued. “There are a couple of suspicious packages that were left behind,” he said, “and we’re waiting for the bomb unit to show up and check them out.” Gromada said he and police departments all along the route prepare each year for all sorts of emergency contingencies, but usually they involve the unpredictable weather, not deadly bombs. He remained in contact with counterparts from his department as well as Massachusetts Emergency Management and US Homeland Security. But that was wore difficult because he wasn’t able to get through on his cell phone to other cell phone numbers. “I think Homeland Security shut down cell-to-cell calls,” he told one of his officers.

Some runners, Gromada said, were being housed at a shelter at St. Ignatius at Boston College. As awful as the incident was, he said, he took solace that it came when it had. “We were lucky it happened near the end,” he said, “when the groups of remaining runners were pretty thin.”

At that point, sirens blared and a black vehicle pulled up, across the intersection from the running show store with the “We (heart) 26.2” in the window. Out of the vehicle stepped a muscular member of the bomb unit, dressed all in black, and leading a black bomb-sniffing dog to the suspicious package. When that package was deemed safe, the dog was led to another package and then to a port-o-potty.

While this was happening, pedestrians continue to arrive at the intersection, asking for police permission to cross to the other side of Centre Street. One mother shouted from one side for her teenage daughter on the other side of the blockade. Three students from Boston College’s Newton campus pleaded for permission to cross. Eventually, the police relented and let them through. “Thank you so much!” the students gushed.

At 4:38 p.m., after the bomb unit had cleared out, heading to another spot along the route to perform the same task, Gromada signaled for the officers to remove the barricades.

That’s when a pair of runners, also wrapped in mylar blankets and walking backwards from Mile 20, headed down Centre Street. Rachel Irving, a 33-year-old from the North End running her first marathon, said the first sign of trouble had come around Mile 19. That’s when she overheard a runner she didn’t know, talking on his cell phone, saying something about a “bomb at the finish line.” Still, he didn’t seem too concerned, so she kept going with her 31-year-old racing partner, Radhika Bhattacharya.

At Mile 20, they learned the news that the bomb report was true and the race was over. Bhattacharya, who lives two blocks from the finish line, called her mother, who was staying in her apartment. Her mother had been planning to leave the apartment shortly and head to the finish line. That all changed when she heard the two blasts. Her mother was worried until she heard her daughter’s voice on the phone. “Luckily, we’re slow,” Bhattacharya said.

Latest report: Two people were killed and 107 were injured.

From Globe Correspondent Justin A. Rice: Thirty-three buses worth of unclaimed runners bags can be claimed now on Berkeley Street in Copley Square, according to race officials.

The bags will be left on the street till dark at which point they will be moved to a safe location.

Share thoughts, prayers, and reaction to today's events bo.st

From the Globe staff: A chaotic scene is unfolding at Boylston and Massachusetts Avenue, with officers blocking off the entrance to Boylston and bewildered runners and spectators calling relatives on their cell phones and trying to make their way out of the area.

Many people are crying, holding hands and locking arms as they navigate the sea of onlookers, police, and National Guard troops directing traffic.

One man got into an angry shouting match with an officer at the top of Boylston, telling him repeatedly, "I got family down there!"

But the officer refused to let the man through and threatened to arrest him if he did not turn around.

The man shouted, "I don't give a [care], I'll go back to prison" before friends led him away.

Karyn Ragonese, 40, of Charlestown, said she was at the 25 and 1/2 mile marker before the runners in front of her "came to a dead halt."

She said that when she heard about the explosions, "I just freaked out because I have a bunch of friends who came with me. I didn't know what the hell was going on. My dad was at the finish line."

She said all of her companions at the race, including her father, have been accounted for.

"A huge relief," she said. "I just called my sister."

President Obama just addressed the nation from the White House press room:

The nation will remember Boston in their prayers tonight. Federal officials are mobilizing resources to help. I've notified leaders of both parties; they agree that on days like this, there are no political parties.

Police, firefighters, first responders, and the National Guard responded heroically. We salute all those who responded so quickly and professionally to this tragedy.

We still do not know who did this or why; we still don't have all the facts. We will get to the bottom of this. We will find who did this and we will find out why they did this. Any responsible individuals, any responsible groups will feel the full weight of justice.

Today is Patriots Day, a day that reflects the freedom Boston has celebrated throughout its history. Boston is a tough and resilient town; so are its people. I'm sure the people of Boston will pull together.

As we get more information, our teams will provide more briefings. We'll find out who did this, and we'll hold them accountable.

Dunkin' Donuts, New Balance, NStar said they have received no reports of any employees being hurt in Copley Square explosions

Dunkin’ Donuts said that it has not received any reports that employees located near the explosions along the Boston Marathon route were hurt, but said that two of its stores are closed as a result of the evacuation of the neighborhood near the marathon’s finish line.

Atlantic Fish Co., a restaurant located two doors east of one of the explosions, currently has “no reports of injury to employees or guests” at the restaurant at 761 Boylston St. or its two nearby sister restaurants Abe & Louie’s and Joe’s American Bar and Grill, according to a statement posted on the company’s website.

All three restaurants are currently closed, and employees and customers have been evacuated.

“The safety of our employees and guests is our highest priority at this time,” said Bryan Lockwood, chief executive of Tavistock Restaurants, which runs the Back Bay restaurants. “We are awaiting additional information and details on the circumstances surrounding this unfortunate incident. Our thoughts and prayers go out to all those who have been affected by this tragedy.”

Meanwhile, New Balance said that its employees are fully accounted for. As a Boston-based maker of athletic footwear, the company had more than 100 employees, guests, and runner on hand for the marathon. New Balance also has a store on Boylston.

Employees at the store felt the blast, but no damage has been reported, New Balance said.

Adidas, another sneaker company, also had a presence at the marathon.

“We are monitoring the situation carefully and are currently in the process of ensuring all of our employees are safe,” an Adidas spokeswoman said.

NStar, which has offices on Boylston Street, said it was unaware of any of its employees being injured.

NStar added that it would defer to city and state officials in deciding whether to have Back Bay employees report to work on Tuesday.

--Jenn Abelson and Erin Ailworth Globe Staff