Connor Bryce Smith had tried his hand at karate and a couple seasons of soccer, but the 6-year-old truly loved to run.
On Wednesday, the Glenelg kindergartner was running in Westminster with his mother, Donna, in his fourth Fun Run, when he collapsed and died of what apparently was an undiagnosed heart abnormality.
The police were alerted shortly after 7 p.m. and found Connor undergoing cardiopulmonary resuscitation on the tailgate of a pickup truck at East Main and North Court streets, said Maj. Ronald Stevens of the Westminster Police Department.
Connor was taken to Carroll Hospital Center, where he was pronounced dead.
The results of the autopsy are pending, according to the medical examiner's office in Baltimore. Connor's parents were told he appeared to have a coronary artery anomaly, said his father, Tim Smith. But it was "something you would have never known," he said. "It was something we certainly never anticipated."
His parents, still reeling from the shock of losing their oldest child, said Connor was thrilled about the race.
The Smiths smiled as they remembered how on Wednesday Connor could not wait to slip on his Batman shirt for the second year in a row to hear people shout "Go, Batman, go!" from the sidelines.
The added incentives of a medal and ice cream at the finish line never hurt, either.
"He was a very athletic and energetic person," said Tim Smith, who ran the race as a child growing up in Manchester. He remembered his son's excitement as they went up the hill to the race.
Taking after his parents, who both ran in high school and college, Connor had started participating in the run at age 3, running a 13:30 mile his first year, a 10:02 his second and a 8:58 his third, his parents said.
"Even at 3, the little fella wouldn't stop once," said Donna Smith, adding that she first experienced the Fun Run with her son. "I loved running with him in the race. I loved cheering him on."
Several pages in Connor's scrapbook commemorated his most recent race, which had landed him in a front-page article in the local paper.
"He was proud of that," said Donna Smith, who wanted to focus on her son's life rather than what happened Wednesday night.
His parents fondly described Connor as competitive and very much an individual, with an intense curiosity about how the world - and everything in it - worked.
His parents said he enjoyed nonfiction books about the solar system, electricity, trains and mechanics. His mother described him studying circuits for hours, and his father recalled him following wires around to their source.
"He was a very deep thinker," diligent and serious with his schoolwork, Donna Smith said.
"He always tried to figure things out," his father added, describing how his son would explain the way electricity came out of the wall and flowed through an extension cord. He and his father created a flashlight using a paper-towel tube, old flashbulb and a battery, Tim Smith said.
They brought out a grandfather clock their son had constructed a couple of weeks ago, using the plastic parts of a toy building set and a pattern. Connor had not told them he was working on it, but he impressed them when he presented the finished product.
"I always told him if he studied hard ... he would do great things," Donna Smith said.
Dr. Robert Wack, director of pediatrics at Carroll Hospital Center, said he pronounced Connor dead Wednesday night at the hospital.
"Whatever it was, it would be something extremely rare," said Wack, also a member of the Westminster City Council. "Kids don't commonly die of heart things."
He said children can safely run competitively at very young ages.
A coronary artery anomaly could be anything from the absence of key artery that supplies blood to the heart to one that is misplaced or too small, said Dr. Bill Howard, who heads sports medicine at Union Memorial Hospital.
The annual mile race along Main Street in Westminster is in its 26th year. It is sponsored by the Westminster Road Runners Club.
"We're all devastated because we all know each other. We're a very close-knit family," said Kevin Dayhoff, who has helped organize the race in years past and spoke on behalf of the club. "We're all upset about it."
Howard, who did not treat Connor, emphasized that, based on the preliminary facts, the mile run would not have caused Connor's collapse.
Children cover several miles in regular play, Howard said, exceeding a single mile run.
"The point to remember is this could have happened doing anything," Howard said. "It could have happened walking up the steps, it could have happened playing tag at school. It could have happened running across the street. ... There is no way anyone would have known about this."
A memorial service for Connor is planned for 10:30 a.m. April 28 at the Nichols-Bethel United Methodist Church in Odenton. Instead of flowers, Connor's parents have requested donations to a Dayton Oaks Elementary School memorial fund in honor of their son, in hopes of adding books on the subjects Connor loved to the library.
Sun reporter Laura McCandlish and freelance writer David P. Greisman contributed to this article.