When a man had a heart attack at a grocery story in rural Minnesota, 20 people lined up and performed CPR on him for over an hour and a half until paramedics arrived - and he survived

It's not very often Dr. Roger White uses the word "amazing." But when more than 20 first responders tirelessly performed CPR on a dying man for more than an hour and a half -- and saved his life -- the co-director of the Mayo Clinic's emergency transport team said it was nothing less than remarkable.

"If he had not had CPR, and good CPR, he would not have survived," White said. "CPR made all the difference."

Watch "World News with Diane Sawyer" for more on this story tonight on ABC.

It was just another cold winter's evening in tiny, remote Goodhue, Minn., where the population is less than 1,000, and they don't even have a traffic light.

Howard Snitzer, 54, was heading to buy groceries at Don's Foods, when he crumpled to the sidewalk, suffering a massive heart attack.

While the grocery clerk called 911, the only customer in the store, an off-duty corrections officer, rushed to Snitzer's side and began what could be the longest, successful out-of-hospital resuscitation ever.

Across the street, Roy and Al Lodermeier, of Roy and Al's Auto Service, heard the commotion and hurried over.

"He wasn't breathing," Al Lodermeier said. "He was in trouble and that's when we started doing CPR."

As news spread, the numbers grew. The team of first responders in Goodhue is made up entirely of volunteers. In total, about two dozen pairs of hands worked to the point of exhaustion to save Snitzer's life in a CPR marathon.

"We just lined up and when one guy had enough, the next guy jumped in," Roy Lodermeier said. "That's how it went."

Candace Koehn, the off-duty corrections officer who was first on the scene, said the group worked as a team.

"Usually," Koehn said, "there was someone on the sidelines saying, 'Hey, you want me to take over? You need a break?'"

When the paramedics arrived via helicopter, they witnessed an astonishing scene. Mary Svoboda, a Mayo Clinic flight nurse who flew in on the emergency helicopter, said "it was unbelievable. There were probably 20 in line, waiting their turn to do CPR. They just kept cycling through."

Read more: http://abcnews.go.com/Health/96-minute-cpr-marathon-saves-minnesota-mans-life/story?id=13048099