At first, he chuckled at the sight of two boys taking a playful ride on a motorbike near Queenstown.
Seconds later, Richard Dudley winced as the unthinkable happened, right there in front of his delivery truck.
Mr. Dudley saw one of the boys fall from the off-road dirt bike and then try to reach up with both arms.
But the left one had been severed below the elbow by the whirring spokes of the motorbike's rear wheel.
Aaron Thompson, 8, lay on the ground, bleeding from his injury and screaming.
But quick thinking by Mr. Dudley, and fast response by local and State Police rescue workers, saved Aaron's life -- and probably the use of his left arm.
Less than 45 minutes after the Eastern Shore accident, which occurred shortly after 4 p.m. Monday, the boy arrived by helicopter at Johns Hopkins Children's Center, where the forearm was reattached in a 10-hour operation by a surgical team led by Dr. Kyle Bickel.
Late yesterday, Aaron of Queenstown was listed in critical but stable condition and remained in the intensive care unit.
His parents, Patrick and Pamela Thompson, were at the hospital.
Surgeons believe the boy's chances of regaining full use of the arm are "very good," said Hopkins spokeswoman Jo Martin.
Aaron was to have a skin graft operation today.
The accident was on Wye Harbor Drive, in a section of Queen Anne's County known as Dennis Point, which is just south of Queenstown.
Jumping from his truck, Mr. Dudley, a 43-year-old father of two and a courier for Federal Express, rushed to Aaron's side and got the bleeding under control by applying pressure.
Mr. Dudley also wrapped the severed limb in his work shirt and a T-shirt.
And he comforted Aaron. "I just told him to hold my hand. He grabbed hold and started talking. He asked me, 'Am I going to die?' " Mr. Dudley recalled yesterday.
He cradled the boy while an unidentified resident of Wye Harbor Drive used a portable phone to call 911 and also Aaron's parents.
In minutes, volunteer rescue workers from the Kent Island station of the Queen Anne's County Fire Department were on the scene, attending to Aaron and icing the severed limb that Mr. Dudley had wrapped so carefully.
Then came a state MedEvac helicopter. Trooper Phil Scott, the duty medic aboard, had this to say about Mr. Dudley.
"The guy who stopped and helped Aaron may have saved his life by applying pressure to his injured arm. With a major injury like that, it would have been very easy for the boy to bleed to death. In a situation like this, every minute is critical."
Trooper Scott of the Centreville State Police Barracks said Mr. Dudley and the volunteer rescue workers "made my job very easy. It was one of those calls when everything went right. They called us right away and kept the boy calm while I took his [vital signs] and made sure he was stable, so it took me only 3 or 4 minutes to get him ready for transport."
Mr. Dudley, who lives in and works out of Dover, Del., recalled yesterday how he administered first aid based on his memory of a basic medical course he received in the Air Force years ago.
"A lot of people would not do that because they're afraid they will get sued," he said. "I just wanted to do the right thing for that little boy."
At first, Aaron was so shocked that he did not want his his injured arm touched. "He was afraid and I can't blame him," Mr. Dudley said. "I talked to him, told him he had to settle down, that he would be all right. . . . He finally caught on."
After the rescue workers arrived, and Aaron was in more expert hands, Mr. Dudley quietly got back into his truck and returned to his delivery route.
"I felt I was in the way and I just went on," he said.
"Do I feel like a hero?" he asked after several people called his office to congratulate him.
"Not really, to be honest. I was just there for someone.
"I hope that if something like that occurs to me, someone would do the same thing," Mr. Dudley said.