It took just one play on Sept. 15 to suggest that the youth football game between the Southbridge Pop Warner peewees and their rivals, the Tantasqua Braves, could mean trouble. Two Tantasqua players were hit so hard that their coach pulled them off the field. An emergency medical technician on the sidelines evaluated the boys, grew worried that they might have concussions, and had them take their pads off.

The boys on the teams were as young as 10 years old and, because of rules about safety, none could weigh more than 120 pounds. Shortly after 3 p.m. at McMahon Field in Southbridge, though, things quickly got worse. Six plays into the game, another Brave was removed after a hard hit. An official with the Tantasqua team said the eyes of one of the boys were rolling back in his head.

But the game, an obvious mismatch between teams from neighboring towns in central Massachusetts, went on, with Southbridge building a 28-0 lead in the first quarter. The game went on without the officials intervening. It went on despite the fact that the Braves, with three of their players already knocked out of the game, no longer had the required number of players to participate.

Even with what are known as “mercy rules” — regulations designed to limit a dominant team’s ability to run up scores — the touchdowns kept coming, and so did the concussions. When the game ended, the final score was 52-0, and five pre-adolescent boys had head injuries, the last one hurt on the final play of the game.

The coaches, at the game’s conclusion, shook hands, and then the Southbridge team, with a military flourish, marched off the field in pairs.

Like almost all Pop Warner games, this one played just over an hour’s drive west of Boston gained little attention. But since then, it has emerged as one of the more disturbing episodes in the ever more controversial world of youth football. In the days after the game, the injured boys were formally determined to have suffered concussions. Some parents accused Southbridge’s players of deliberately trying to hurt their sons. Scott Lazo, Southbridge’s coach, accused the Tantasqua coach of not properly training his team and jeopardizing them by not forfeiting.

“If you lost that many players, you should have called a timeout and come seen me,” Lazo said in an interview this week. “My team is not dirty. All the issues were on their side of the field. This is a football game, not a Hallmark moment.”

Late last week, league officials suspended the coaches for both teams for the rest of the season. The referees who oversaw the game were barred from officiating any more contests in the Central Massachusetts Pop Warner league, and the presidents of both programs were put on probation.

But the debate the game has further fueled is not likely to calm any time soon. Head injuries in the National Football League remain the league’s greatest safety concern, and the league’s greatest legal liability. Schools in the Ivy League have ordered limits on contact in football practice, so as to reduce the risk of brain injuries. And Pop Warner, the national organization made up of hundreds of thousands of children, some as young as 5, has adopted its own safety guidelines, based in part on the medical wisdom that the brains of young boys are particularly vulnerable.

Still, as the Massachusetts game suggests, rules are only as effective as the adults charged with enforcing them. Four of the five injured boys have resumed playing football for Tantasqua.

The football rivalries, passion and pride can interfere with common sense. A banner on Southbridge’s website asks, “Are You Tough Enough?” Lazo has coached in Southbridge for 18 years and says he idolizes Vince Lombardi, the Hall of Fame pro coach who was once said to declare, “Winning isn’t everything; it’s the only thing.” Yet even as the Southbridge team pummeled Tantasqua that day, parents on the losing side of the field wanted their sons to soldier on.

“We were trying to play a football game,” one parent of a Tantasqua player wrote in an email. “Every kid who was out there wanted to play and not give up.”

Pop Warner has done more than perhaps any other organization to try to protect young players from head injuries. In 2010, the league told its coaches that if there is any doubt about a child’s health, the player is to be removed from play. Coaches receive training in how to recognize concussions, and once a player is removed because of a concussion, he needs a doctor’s note to return to games. In June, Pop Warner told its coaches to limit player contact in practices and to eliminate full-speed head-on blocking and tackling drills.

Yet on any given Saturday, the rules may be bent or ignored, even by referees under pressure from parents and coaches.

“Having been there and coached, the game officials should have been more cognizant with this many kids going down and seeing the sidelines and the same kids going out there,” said Kevin Guskiewicz, the founding director of the Matthew Gfeller Sport-Related Traumatic Brain Injury Research Center at the University of North Carolina, who advises the NCAA and NFL. “What in the world was the coach thinking?”

Erik Iller, Tantasqua’s coach, could not be reached for comment.

Guskiewicz, whose three sons played Pop Warner football, said that it is often difficult to diagnose concussions in younger players because the injuries are invisible and the player must describe how he feels. Because teams are coached and organized by volunteers, the quality of care on the sidelines varies widely. Few leagues require that a physician be present, he said.

Officials with the Central Massachusetts Pop Warner league did not seek to inquire into the Southbridge-Tantasqua game until parents began to complain a week later. Even then, it took several weeks to hear from the coaches and officials.

The hearing took place last Thursday at a hotel in Worcester. The coaches and the team presidents were there, and parents milled around outside the hearing room. The meeting lasted about four hours and ended at about midnight.

In a statement after the meeting, Patrick Inderwish, president of the Central Massachusetts Pop Warner league, said, “Nothing is more important to Pop Warner than the safety and well-being of our players.”

Lazo, the Southbridge coach, said the league committee that conducted the hearing told him he should have taken his team off the field. He insisted, though, that he was not aware of the accumulating injuries on the other sideline.

He said the coach of Tantasqua, Iller, told the committee he had his team continue because he wanted the boys to score, and thus “leave with something.”

“It’s shocking there were five concussions diagnosed because it means there were probably many more,” said Chris Nowinski, president of the Sports Legacy Institute, a nonprofit organization involved in research on brain trauma among athletes and members of the military. “And with a roster that small, the kids might have felt pressure to keep playing.”

Speaking generally about youth coaches, he said, “If you consider the coach is a fool, there are no rules that are foolproof.”