A Michigan judge ruled that the Oxford school district and its staff cannot be sued over the 2021 mass shooting when then-15-year-old gunman Ethan Crumbley killed four students and wounded seven others. 

In an order Friday, Oakland County Circuit Judge Mary Ellen Brennan dismissed Oxford Community Schools from civil lawsuits related to the shooting, arguing the district and more than a half dozen high school employees are protected by governmental immunity. 

Several lawsuits filed by survivors and the families of the deceased had accused the district and staff of negligence, gross negligence and violation of the Child Protection Law, among other claims. 

For months, Crumbley allegedly demonstrated "concerning behavior that indicated psychiatric distress, suicidal or homicidal tendencies and the possibility of child abuse and neglect," at least one of the lawsuits alleged, according to ABC News. 

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The civil lawsuit now leaves Ethan Crumbley and his parents, Jennifer and James Crumbley, as defendants, The Washington Post reported. 

"The court concludes that Ethan Crumbley's act of firing the gun, rather than the alleged conduct of the individual Oxford defendants, was ‘the one most immediate, efficient, and direct cause of the injury or damage'," Brennan wrote.

"On behalf of our Oxford clients, we are deeply saddened and disappointed by Judge Brennan’s dismissal today of all the Oxford Community Schools defendants," Detroit-based attorney Ven Johnson said in a statement, announcing that he plans to appeal Brennan’s ruling to the Michigan Court of Appeals. "We maintain that governmental immunity is wrong and unconstitutional, and the law should be changed immediately."

Ethan Crumbley, now 16, pleaded guilty in October to terrorism and first-degree murder charges. 

Authorities say he used a semi-automatic handgun to open fire on Nov. 30, 2021, on other teenagers in the hallway at the school roughly 30 miles north of Detroit. The four students who were killed were 16-year-old Tate Myre, 14-year-old Hana St. Juliana, 17-year-old Madisyn Baldwin and 17-year-old Justin Shilling.

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Prosecutors have said they’ll seek a life sentence with no chance for parole.

Jennifer and James Crumbley, meanwhile, have pleaded not guilty to four counts each of involuntary manslaughter. 

On the morning of the shooting, authorities say the parents were summoned to the school but refused to take their son home following a 13-minute meeting. They were told to get the teen counseling after a teacher saw Crumbley looking at ammunition on his phone while in class a day earlier. The parents were also confronted over the teen's drawings, which included a handgun and the words: "The thoughts won’t stop. Help me."

The Oakland County sheriff and prosecutor Karen McDonald have both condemned the school district for failing to alert a school resource officer about their concerns with Crumbley and not searching the teen’s backpack before allowing him to return to class about three hours before the shooting.

In bringing charges against the parents, McDonald accused James and Jennifer Crumbley of failing to keep the gun used in the shooting secure at home and failing to reasonably care for their son when he showed signs of mental distress. Michigan's Supreme Court ordered the state appeals court to hear an appeal from the couple who face trial.

Ethan Crumbley, when pleading guilty, admitted his parents used his own money to buy him the gun, which was kept in an unlocked safe at their home. 

The Associated Press contributed to this report.