Editor's Note: The videos in this story, shot by John Walls, don't show anything graphic, but they really show the chaos and fear of the moment. Katie Walls, his daughter is an account manager at WTOP.
WASHINGTON -- By this time, it had become routine.
The Boston Marathon was something of a tradition for the Walls family of Arlington, Va. Last year's race was Cindy's 18th. Her daughter, Katie, had entered for the first time.
John, who had run the race before, had a seat in the grandstand at the finish line on Boylston Street, with a smartphone in hand to track the progress of his wife and daughter.
"It was a very exciting day," he says. "They were running together."
John had seen the two at the 10-mile mark. A little more than three hours after the mother-daughter tandem took off, he arrived at the grandstand with some family friends.
He wanted to prepare for the moment they would cross the finish line, so he took out his smartphone for some trial-run video recordings.
Then the first bomb exploded.
"I'll never forget that moment," he says. "We knew it was an explosion of some type, but didn't think about a bomb. That never occurred to me."
From where they were, he felt the heat and the rush of wind, and sensed the acrid smoke.
Shortly after the initial shock, a second explosion went off, this time adding a message to the fear.
"There really was an extraordinary terror that you felt," John says. "You realize that it was something that was orchestrated, this was an act of some kind of violence, and now, 'Where's next?'"
While people in the grandstand frantically cleared out, Cindy and Katie continued running. They were about one mile from the finish line, oblivious to what had happened.
John supposed they were unaffected by the two explosions. But at that early stage, no one knew if more were still to come.
He started asking whether anyone had heard more explosions away from the finish line.
"Even talking about it now, I get that feeling in my knees that you get when you almost have a car wreck," he says.
Cindy and Katie, along with other runners, weren't allowed to finish the race -- an order Katie didn't take well before learning what had happened.
Then, the family struggled to reconnect. About two hours after the bombs detonated, John, Cindy and Katie found each other.
"It was the greatest feeling, to see the two people that you love more than life itself and they're OK, and they knew you were OK," he says. "That was pretty special."
The family plans to return to the Boston Marathon on Monday. Cindy and Katie will run once again. And John will be in the same place in the grandstand, ready to capture the moment.
© 2014 WTOP. All Rights Reserved.