The parents of a young football player who was pummeled by a mob of teammates in a locker room at Woburn Memorial High School in 2021 filed a federal lawsuit Thursday against city and school officials, alleging they permitted a toxic culture in the football program that promoted bullying and violence.

Jeanny and Kevin Coucelos, whose son Johnathan was a 14-year-old freshman at the time, asserted that Woburn authorities caused additional harm, including severe emotional distress, by failing to adequately respond to the attack, according to their complaint in US District Court in Boston.

“With the filing of this complaint, the Coucelos family takes the next step in seeking justice for the series of outrageous attacks on an innocent young man at Woburn Memorial High School and to hold those in charge accountable for the damage done,” said their attorney Peter Hahn of the OneLaw firm in Newton.

Woburn school and city officials did not respond to requests for comment.

Five football players were charged in Lowell Juvenile Court after the locker room ambush, including one who faces an additional count of indecent assault and battery for allegedly groping Johnathan Coucelos’ genitals. Two other students were charged as juveniles with assaulting him at school after the locker room episode.

Several of the students have been sentenced to community service. The charges against the player who faces the indecent assault and battery count are pending. That student has been allowed to continue playing for the Woburn football team, which opens its season Friday at home against Longmeadow.

Jonathan Coucelos, his parents, and Hahn have criticized Woburn officials for allegedly failing to hold any adults accountable for the attack and its aftermath.

“I want to see everybody who was involved held liable for what they did and for trying to cover it all up,” Johnathan Coucelos said Thursday through his father.

Woburn’s head football coach Jack Belcher remains on the job, as does athletic director Jim Duran. Specialists in student-athlete safety say coaches are responsible for monitoring and protecting players in their programs, and athletic directors are responsible for ensuring coaches perform those duties. Belcher and Duran have said they were not present during the attack.

“I want the administrators and coaches held accountable for their actions,’’ Kevin Coucelos said. “Those coaches should have been long gone. Instead, administrators are dragging their feet, putting other kids at risk of getting bullied.”

The Woburn principal at the time of the attack, Jessica Callanan, later departed for Reading Memorial High School. Also gone is Chase Andrews, a volunteer assistant football coach who Johnathan Coucelos’ parents allege failed to properly respond when Coucelos reported the beating to him.

Belcher, Duran, Callanan, and Andrews are among those named as defendants in the lawsuit, as are Woburn Schools Superintendent Matthew Crowley, the Woburn School Committee, and Mayor Scott Galvin.

A federally mandated Title IX review of the case conducted by an independent investigator, before a final review by a school official, cited statements from Andrews and Woburn’s head freshman coach Chris Scichilone that they were not formally trained about hazing before Johnathan Coucelos was accosted.

The review found that “the team assault was planned, organized, and executed by a substantial number of sophomore players.” One player said he punched Coucelos multiple times after the sophomores — “like 30 kids” — decided “to beat up Johnathan.”

The family’s lawsuit alleges that Woburn’s coaches did not receive the proper training in bullying and hazing until after the attack.

Woburn officials commissioned a separate independent investigation of the case by former state secretary of public safety Daniel Bennett, but they have refused to publicly release Bennett’s final report. Instead, Crowley issued a statement last year stating that the investigation concluded “the district generally had proper policies and procedures in place and timely responded to the incident by developing appropriate safety plans for the student consistent with national standards.”

Hahn said Woburn officials have made no attempt to settle the case since Coucelos’ parents notified the city 19 months ago of their intent to sue. They are seeking $750,000, “or a greater amount if warranted by the evidence at trial,” according to their complaint.

The beating has upended Johnathan Coucelos’ life, his parents said. He has withdrawn from the Woburn school and suffered extreme emotional distress. The complaint states that he has been diagnosed with depression, anxiety, and post-traumatic stress disorder stemming from the experience.

Belcher, who has yet to publicly address the incident, has been Woburn’s head coach since 2017. The lawsuit states that no member of his staff was supervising the team at the time of the attack and that no coach intervened, even though a coach’s office was directly across the hall.

The lawsuit cites two other cases of alleged abuse in Belcher’s program. In 2018, Belcher allegedly witnessed an older player kick a younger one so hard in the head that the younger player became immediately ill, yet the coach took no action. Another player, who graduated in 2021, said that as a freshman he was bullied and beaten by older teammates, according to the complaint.

“Coach Belcher had encouraged stronger players to toughen up the weaker ones,” the lawsuit alleges. It states the parents of the player who was kicked in 2017 “spoke to Coach Belcher and reported the behavior to Principal Callanan, but nothing changed.”