OXFORD TOWNSHIP, MICH. -- A judge has ordered a Michigan boy charged in the shooting at Oxford High School to be moved from a juvenile facility to a county jail.

Ethan Crumbley will be held without bond on charges of murder, attempted murder, terrorism causing death and gun crimes. He is charged as an adult, but has been held in a juvenile facility since Tuesday's shooting that killed four students and injured seven other people.

Judge Nancy Carniak said during Crumbley's arraignment hearing Wednesday that she would "err on the side of caution" and approve Crumbley's transfer. Crumbley's defense attorneys had objected to the move.

THIS IS A BREAKING NEWS UPDATE. AP's earlier story follows below.

OXFORD TOWNSHIP, Mich. (AP) -- A 15-year-old boy was charged with murder and terrorism for a shooting that killed four fellow students and injured others at a Michigan high school, authorities said Wednesday, revealing that his parents were summoned just a few hours before the bloodshed.

No motive was offered by Oakland County authorities, a day after violence at Oxford High School, roughly 30 miles (50 kilometers) north of Detroit. But prosecutor Karen McDonald said the shooting was premeditated, based in part on a "mountain of digital evidence" collected by police.

"This was not just an impulsive act," McDonald said.

Oakland County Sheriff's Lt. Tim Willis said during a court hearing for Ethan Crumbley that the boy recorded video the night before violence in which he discussed shooting and killing students.

The revelation was made by Oakland County Sheriff's Lt. Tim Willis during a court hearing for Ethan Crumbley. Willis made the comments shortly before Crumbley was to be arraigned on charges of murder, attempted murder, terrorism causing death and gun crimes. He is charged as an adult. It wasn't immediately known if he had an attorney who could comment.

Sheriff Mike Bouchard told reporters that Crumbley's parents were called to the school Tuesday "for behavior in the classroom that was concerning." The teen remained in school, and the shooting occurred a few hours later.

Bouchard didn't offer details about what had troubled school officials. He said investigators believe the gun was already in school.

"There is nothing that he could have faced that would warrant senseless, absolutely brutal violence on other kids," the sheriff said.

The shooting should be a wake-up call for new gun laws in a country that has become "desensitized to school shootings," McDonald told reporters.

"We have to do better," McDonald said without offering specific changes. "How many times does this have to happen? How many times?"

She said the terrorism charge also fits.

"What about all the children who ran, screaming, hiding under desks? ... Those are victims, too, and so are their families and so is the community," McDonald said.

Deputies rushed to the school around lunchtime Tuesday and arrested Crumbley in a hallway within minutes of the shooting. His father bought the 9 mm Sig Sauer gun last week, according to the sheriff.

McDonald said charges were being considered against the parents.

"Owning a gun means securing it properly and locking it and keeping the ammunition separate," she said.

The four students who were killed were identified as 16-year-old Tate Myre, 14-year-old Hana St. Juliana, 17-year-old Madisyn Baldwin and 17-year-old Justin Shilling.

After the attack, authorities learned of social media posts about threats of a shooting at the roughly 1,700-student school. The sheriff stressed how crucial it is for such tips to be sent to authorities, while also cautioning against spreading social media rumors before a full investigation.

Isabel Flores, a 15-year-old ninth grader, told Detroit television station WJBK that she and other students heard gunshots and saw another student bleeding from the face. They then ran from the area through the rear of the school, she said.

A concerned parent, Robin Redding, said her son, 12th-grader Treshan Bryant, stayed home Tuesday after hearing threats of a possible shooting.

"This couldn't be just random," she said.

Bryant said he had heard vague threats "for a long time now" about plans for a shooting.

At a vigil Tuesday night at LakePoint Community Church, Leeann Dersa choked back tears as she hugged friends and neighbors. Dersa has lived nearly all of her 73 years in Oxford. Her grandchildren attended the high school.

"Scared us all something terrible. It's awful," Dersa said of the shooting.

Pastor Jesse Holt said news of the shooting flooded in to him and his wife, including texts from some of the 20 to 25 students who are among the 400-member congregation.

"Some were very scared, hiding under their desks and texting us, `We're safe, we're OK. We heard gunshots, but we're OK.' They were trying to calm us, at least that's how it felt," he said.

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Associated Press journalists Ryan Kryska, Mike Householder and David Aguilar in Oxford Township, Michigan; Kathleen Foody in Chicago; and Josh Boak in Rosemount, Minnesota, contributed to this report. AP researcher Rhonda Shafner in New York also contributed.

Correction:

The spelling of one of the victim's names has been corrected to Hana St. Juliana, instead of Hanna St. Julian.