A 12-year-old student faces a hate crime charge for her alleged involvement in an attack on twin Muslim students at their Connecticut middle school, authorities and advocates said. The physical altercation happened earlier this month at Wallace Middle School in Waterbury, Connecticut.

Through a summons to juvenile court, the accused student was charged with intimidation based on bigotry and bias in the first and second degree, according to the Waterbury Police Department.

Police said in a statement that investigators probing the March 3 incident “determined that the altercation was motivated by religion and/or ethnicity, meeting the definition of a hate crime.” They also said the classification was reviewed and confirmed by the Waterbury State’s Attorney’s Office.

Another 13-year-old student accused in the altercation was referred to a youth diversionary program instead of being arrested, according to police, “based on her involvement in the incident.” Police said their investigation included interviews with students and staff at the school “who were present or otherwise involved” in the incident.

The students’ names were not released by authorities.

According to the Connecticut chapter of the Council on American Islamic Relations, the students were targeted for wearing hijabs. CAIR’s chair Farhan Memon spoke out about the incident in an interview with the FOX affiliate station WTIC-TV. CAIR has reposted the interview to its social media platforms and website, alongside information about the alleged assault.

Both sisters suffered injuries in the altercation, which police characterized as minor. They did not require immediate medical treatment at the scene of the attack, according to police, but CAIR said the injuries were “severe enough to require treatment at a hospital.” The organization, which advocates for Muslim civil rights and against Islamophobia in the U.S., called the attack “brutal” in a March 12 post on Facebook.

“The parents of the victims sought CAIR’s assistance because they felt that they were not receiving sufficient communication from the school regarding disciplinary actions against the perpetrators or a clear plan to ensure their daughters’ safety,” the organization said.

The Waterbury Department of Education has now acknowledged the incident as an act of bullying, police said, adding that education officials have “taken disciplinary action, and implemented enhanced school safety measures in response to the incident.”

“While this was not part of a widespread problem, this is an opportunity to reaffirm our commitment to ensure our students are safe and respectful of one another,” said Darren Schwartz, interim superintendent of Waterbury Public Schools, in a statement.

The Waterbury Police Chief said in a separate statement that his department is committed to taking seriously claims of bias-related incidents, adding the investigation into this one “reaffirms our commitment to maintaining a safe and inclusive school environment.”

Spokespeople for the police and education departments in Waterbury directed CBS News to their public statements about the altercation in response to a request for comment and more details.