OXFORD TOWNSHIP, Mich. — The parents of a teenager accused of killing four students at a Michigan school were summoned to discuss his behavior just a few hours before the violence, a sheriff said.

The disclosure was made Wednesday as Ethan Crumbley, 15, was charged as an adult with two dozen crimes, including murder, attempted murder and terrorism for a shooting Tuesday at Oxford High School in Oakland County.

“He deliberately brought the handgun that day with the intent to murder as many students as he could,” assistant prosecutor Marc Keast said while successfully arguing for no bail for Crumbley and a transfer to jail from a juvenile facility.

No motive was offered. But prosecutor Karen McDonald said the shooting was premeditated, based on a “mountain of digital evidence” against Crumbley.

Investigators found that he had recorded a video the night before the bloodshed in which he discussed killing students, Lt. Tim Willis of the sheriff’s office said.

“This was not just an impulsive act,” McDonald told reporters.

During his arraignment, Crumbley replied, “Yes, I do,” when asked if he understood the charges. Defense attorney Scott Kozak entered a plea of not guilty.

Earlier, 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, however, and the shooting occurred a few hours later.

Bouchard didn’t say what had worried school officials. He said investigators believe the gun was already in the 1,700-student school. (AP)