The leader of Oxford Community Schools fired back on Tuesday at a lawsuit alleging that the district failed to heed warning signs before the shooting that killed four students in November.

       MORE: 4th student dies from Michigan school shooting; 15-year-old charged as adult: Latest

       In a letter to parents, Superintendent Tim Throne said that the district was unaware of a message on Ethan Crumbley's Twitter account the night before the shooting that read: "See you tomorrow, Oxford," until after the shooting occurred.

       Emily Elconin/Getty Images

       A memorial outside of Oxford High School, Dec. 7, 2021, in Oxford, Mich.

       Throne's statement contradicts allegations made by attorney Geoffrey Fieger, on behalf of two Oxford High School students, that Throne and the principal "reviewed the social media posts of Crumbley prior to November 30, 2021, which threatened Oxford High School students."

       Throne also said that an investigation into an incident three weeks before the shooting, in which a severed bird's head was found in a bathroom at the school, "determined there was no threat to the high school." Law enforcement was "unable to determine when or how the jar was delivered," he added.

       The lawsuit contended that Crumbley placed the bird's head in the bathroom and that school leaders assured parents afterward that there was "absolutely no threat at the high school," even though parents voiced concerns about their children's safety.

       Emily Elconin/Getty Images

       Oxford High School in Oxford, Mich., Dec. 7, 2021.

       On Tuesday, Throne said he was "proud" of school administrators, who, he said, "ran toward the incident to effectively save children, administer aid to injured parties, and locate the perpetrator, putting themselves in harm's way."

       Oakland County prosecutors have not brought charges against the school district.