The holiday afternoon spiraled from pleasant to disastrous in an instant. In the time it took for a California beachgoer to apply sunscreen to one of her children, her other child — just 3 years old — had vanished from the beach.

The woman’s son, Brooks, was only a toddler. He could not have strayed far. But when she was unable to catch sight of him, panic started to set in. The woman — whose name is not being reported — tried to call for help, but her plea fell on mostly deaf ears. There were dozens of other beachgoers nearby. After all, it was Saturday afternoon of Independence Day weekend in Newport Beach, Calif.

But none of the vacationers in the area seemed to pay her any mind.

To the two men from Mesa, Ariz., the scene unfolding at the other end of the beach was odd. The brothers — 50-year-old twins Stuart and Steven Frost — were surprised by both the woman’s distress and the apparent nonchalance of everyone else.

The stranger had her hands on her head and was visibly distraught, Stuart Frost would later tell the Arizona Republic. “She was around like 50 people, and none of them got up to help her,” he said. “It was really odd.”

The Frosts’ nephew, 35-year-old Jesse Martin, came sprinting to where his uncles and the rest of the family had gathered for a reunion on the beach. Martin had overheard a pair of women trying to recruit lifeguards to help find a missing boy, according to the Orange County Register. That was the Frosts’ cue — there would be no standing around for this family. Some 30 family members ran to the woman’s aid.

As Brooks’s parents searched the ocean, the new arrivals fanned out over the beach. Martin and his uncles spied a group of children digging in the sand, not far from where the woman had last seen her son. That was the best lead they had. The men bent down and began tearing up the beach by the fistful.

Martin brushed something with his fingertips — a pair of blue swim trunks. It was Brooks. “After a couple big scoops I felt him under there,” he told the Register. Martin hoisted the boy out of the ground by his waist. Brooks had been trapped no more than a yard away from his mother, Stuart Frost told Fox 10.

It was a distressing sight. “He was ash gray, he was dead. He was dead,” Frost told the Republic. “So we pulled him out, and the mom was just beside herself.” Sand caked Brooks’s mouth, and the blood had drained from his face.

The men moved quickly. Both Stuart and Steven Frost knew CPR — they worked as an orthodontist and an endodontist, respectively, according to Arizona’s 12 News. A few chest compressions later, Brooks stirred to life.

“Brooks’ tongue moved and I said, ‘Steve this is working, keep going’ … all of a sudden his lip quivered and I said, ‘Steve, he’s coming back keep going,'” Stuart said in an interview with KPNX’s 12 News.

Brooks was lucky. Newport Beach lifeguards recommend that holes be dug no more than a foot down. Brooks had been crawling through a tunnel about 3 feet deep, authorities told the Orange County Register, that a group of children were trying to connect between two holes.

Tunnels constructed by children, whether made of sand or snow, are not always safe. “Since children aren’t structural engineers, their tunnels aren’t generally sound enough to be crawling through them,” Michigan’s Frankenmuth Police Department wrote on Facebook in February 2014, in an attempt to crack down on snow tunnels.

Truly dangerous collapses are rare, experts say. But if children are completely submerged, the odds of survival are not in their favor, note researchers from Harvard University and the Minneapolis Heart Institute Foundation. In a 2007 letter to the New England Journal of Medicine, the scientists reviewed 52 incidents that occurred during the previous decade. Sixty percent of the collapses were fatal; in the other 40 percent of cases, survival hinged on “timely rescue” and, frequently, CPR.

Death typically comes from asphyxiation, either as sand fills the throat or the weight of the collapse bears down upon the chest. A cubic foot of sand weighs about 100 pounds, and wet sand can add an additional 20 pounds.

Brooks spent no more than 5 minutes underground. Responders took him to Hoag Memorial Hospital Presbyterian, where he made a quick recovery. A few hours after the rescue, Brooks’s family snapped a photo of the smiling toddler and passed it along to the Frosts.

And as Stuart Frost rode his bike along Newport Beach on the Fourth of July, he once again encountered Brooks’s family. This time, the meeting was joyful.

“We just shared the most beautiful experience hugging each other and crying together,” Frost told 12 News on Tuesday. “And, wow, you talk about a happy ending — just spectacular.”