The screenshot taken from the streaming of ABC7 New York shows Jennifer Crumbley, whose then 15-year-old son Ethan Crumbley killed four students and injured 7 others at the Oxford High School on Nov. 30, 2021, entering the court. [Photo/Xinhua]

The parents of a mass shooter at the Oxford High School shooting in U.S. state of Michigan were sentenced on Tuesday to 10 to 15 years in prison for involuntary manslaughter during a sentencing hearing in a Michigan courtroom.

This is the first time in the United States that parents have been charged and convicted in their child's mass shooting at a school.

Ethan Crumbley, then 15 years old, opened fire inside his school, the Oxford High School, on Nov. 30, 2021, killing four students and injuring 7 others. His parents were arrested after days of chase by the police.

Separate juries in Oakland County convicted Jennifer and James Crumbley in February and March, respectively, of four counts of involuntary manslaughter each for deaths of four students killed by their son in November 2021. Ethan, now 17, pleaded guilty as an adult to the 2021 shooting at Oxford High School in suburban Detroit and has been sentenced to life in prison.

Before giving her sentence, Circuit Court Judge Cheryl Matthews said the convictions were not about poor parenting, but confirmed the repeated actions or lack of actions by the Crumbleys, local media reported.

The sentencing grids gave guidelines for what sentences the Crumbleys can receive. And the guidelines take into account a defendant's prior criminal record and specific issues related to the offense.

Prosecutors argued that Jennifer and James were grossly negligent in the 2021 shooting, ignoring warning signs about their son's declining mental health, not telling school officials the family owned guns when they met with school officials the morning of the shooting to discuss a disturbing drawing Ethan had drawn on desk.

Prosecutors also argued the Crumbleys bear responsibility for the shooting because they did not secure the family's guns.

Prosecutors called for 10 to 15 years in prison, highlighting the couple's lack of remorse.