CHELMSFORD — A School Committee meeting erupted into chaos Tuesday as teachers and parents argued with school officials over the handling of a situation that led to Chelmsford Federation of Teachers President Jennifer Salmon being placed on leave.

Dozens of union members from Chelmsford and communities around the state showed up to support Salmon, standing outside in the rain for more than an hour ahead of the meeting.

Salmon, a third-grade teacher at Harrington Elementary School, was placed on leave the day before Thanksgiving following an altercation involving an American Federation of Teachers field representative and school administrators. They had sought a meeting with administrators to discuss a situation involving a first-grade classroom at the school.

Salmon finally broke her silence, speaking during the public input session to thank her supporters and discuss how the situation has affected her and her family.

“This is not about me, nor has it ever been,” she said. “It’s not about my own class, or my own children. It is about us. And while it is uncomfortable sometimes to have these conversations, it is important for the union to not only be a voice for our members but an advocate for our students.”

Salmon also shared a letter from her son to Superintendent Jay Lang saying how he has “greatly impacted my family by not allowing my mom to teach.”

School Committee Chairman Al Thomas gaveled and the committee’s attorney told her not to speak of the personnel matter repeatedly but Salmon continued through the end.

Her husband, John, was also gaveled when he began to venture into similar territory.

The union filed a lawsuit against the School Committee at the state Department of Labor Relations Tuesday, alleging the committee and Lang broke the law by placing Salmon leave without cause, discrediting her and investigating her for potential discipline, issuing a gag order on her and publicly discouraging teachers from seeking union help on matters of classroom safety.

Several staff members and parents spoke in support of Salmon and criticized school administration for its handling of the situation.

Three first-grade teachers from Harrington said they had gone through the proper channels with concerns about safety and the emotional needs of their students. They said that when they did not receive the supports they requested, they went to Salmon and the union for help.

Union Executive Vice President Marie O’Donnell, a teacher at Byam Elementary School, said the elementary schools do not have the supports to handle students’ behavioral needs, and blasted Lang for spending money on office renovations.

“It should be about the kids, and you should all be ashamed of yourselves,” she said.

Kathryn Lebel, mother to a first-grade student, said school communication about classroom situations has been poor.

“I have my 6-year-old, coming home telling me that she was removed from the classroom because of a scary situation,” she said. “I should have known that day what the scary situation was before I even got to have a conversation when I got home from work with her.”

Stephen MacCormack, a parent who organized a peaceful protest outside of Harrington last week, blasted school leadership, saying it lacks the ability to appropriately handle situations and damage control.

When Thomas asked him to wrap up his statement as he neared his three-minute limit, MacCormack pushed back, saying Thomas had promised he wouldn’t gavel him. Thomas said he was subject to the same rules as the other speakers. Several audience outbursts ensued.

Thomas threatened to end the public input because it was getting out of hand. He followed through on that promise after a brief recess, leading to another outburst from some attendees who police then asked to leave. As the chaos continued, Thomas asked police to clear the room so the committee could continue with its agenda.

“It’s a shame that you don’t want to hear the truth,” MacCormack said.

Union members and parents took issue with how the meeting was handled. They said they were told they would be allowed into the room much earlier than they were, and were surprised by an occupancy limit of 49 people — including the committee — enforced by police and fire officials. They accused school officials of allowing others in to fill seats to limit their presence and public input.

Kim Hobbs, who didn’t get a chance to speak, said her first-grade child and others in the classroom have been hit and injured by other children and no one in the school made any attempt to notify parents.

“We understand there’s confidentiality issues,” she said. “We don’t need to know the names of the kids. The kids tell us that. But we need to be notified when our kids are hurt or affected.”

Union Treasurer Erica Arrington said she was disappointed the committee did not allow the remaining parents to speak, and felt it “speaks volumes” to how their opinions are valued.

Follow Alana Melanson at facebook.com/alana.lowellsun or on Twitter @alanamelanson.