When the ice became too thick for his hands and fists to crack, he jumped on top of it, hoping his weight could puncture it. The further into the pond he went, the deeper it became, he said. The frigid water soon reached his neck. Thompson couldn't reach the bottom of the pond but felt reeds near his toes. He floated along them, using them as a guide.
His chest was constricting from the cold water and he was having trouble breathing, he said. He became desperate as time passed, and with it the likelihood of the boy's survival. Then he looked back at the shore.
"Those people were standing on the shore and looking over at me," he said. "I remember what it was like going to the shore and telling people I wasn't able to rescue their child. I gave it that one extra pass to try to find that little boy."
He called out, "Come on little buddy, where are ya?" though he knew the boy couldn't hear him.
Then he saw the boy's body float up from the ice. He grabbed him and put his arm under him to lift his head out of the water, then started to swim, pulling the boy back to shore.
"Just make it back to shore, just make it back," he said to himself, KSL.com reported.
Officials estimate the boy was in the cold water for about 30 minutes. Once on shore, a helicopter took him to Primary Children's Hospital. Hospital officials could not be immediately reached for comment.
The boy was still there, breathing but sedated, as of Tuesday afternoon, friends and family told KSL.com. The extent of his injuries aren't clear. His dog survived, sheriff's officials said.
Thompson told KSL.com the boy was able to survive in part because of the cold water.
"That slows down their metabolism, all their body functions," he told reporters. "And kind of forces the blood back into the main systems."
The Minnesota Department of Natural Resources advises those who fall through ice not to panic and to turn toward the direction they came from, where ice is probably strongest.
The person should place their hands and arms around the unbroken surface and kick their feet until they slide back onto solid ice. They should lie flat on the ice to distribute their body weight, which might prevent them from breaking the ice again. The department then suggests the person roll away from the hole.
For those rescuing anyone who has fallen through ice, the department suggests they not run up to the edge of the hole. Instead, they should shout to the victim advice and encouragement for escaping the hole and, if possible, throw something towards them, such as a rope or a ladder. A light boat can also be used to safely reach a victim submerged in water.
Thompson was in the water for several minutes, rescue officials told KSL.com. He was taken to a hospital and treated for hypothermia and cuts. He suffered nerve damage in his hands and needed stitches for a cut on the forearm he used to break through the ice. He was released from the hospital Monday, but said he couldn't sleep that night.
He said he became interested in rescue diving about 18 years ago when he was having fun with friends diving off cliffs. A diver who was not with his group went under and did not come back up. The rescue crew that arrived asked everyone around, including Thompson, for help. They recovered the diver but could not save him.
Soon after, Thompson trained and became a certified rescue diver. He has been on several underwater rescue efforts through the years, but he's never rescued anyone who has survived.
"It's not me, it's us. I think that's the real story here. I was just the one that went in the water," he told reporters, according to KSL.com. "If there was a hero that night it's us, it's not me." Lieutenant David Crouse, spokesman for the Washington County Sheriff's Office, said officers would have never asked Thompson to dive into the pond.
"This choice of his to go in was deeply personal," he said. "He knew the dangers and he still went in."
