DETROIT (AP) — The Michigan Supreme Court on Wednesday dismissed appeals by families of students killed or wounded at Oxford High School in 2021, ending efforts to hold employees partly responsible for the mass shooting.

Under Michigan law, immunity is a high hurdle to overcome in lawsuits against a government body, including public school staff. Lawyers typically have to show that gross negligence occurred.

The court, in a two-sentence order, said it would not step into the litigation. The decision means a 3-0 Court of Appeals decision in favor of school employees will stand.

A lawyer for the families said he would speak at an afternoon news conference.

The appeals court in September said there was no evidence that Oxford staff were the “proximate cause” of the tragedy, noting it was 15-year-old Ethan Crumbley who “made the definite and premeditated decision” to take a gun to school, kill four students and wound seven other people.

Before the shooting, he sketched images of a gun, a bullet and a wounded man on a math paper, accompanied by despondent phrases. His parents were quickly called to a meeting at school but declined to take him home.

No one — parents or staff — checked the boy’s backpack for a gun, though an administrator joked that it was heavy.

Crumbley, now 19, is serving a life prison sentence. His parents, James and Jennifer Crumbley, are each serving 10-year sentences for involuntary manslaughter. Prosecutors said they had ignored his mental health needs, bought him a gun as a gift and then failed to safely secure it.