OXFORD TOWNSHIP, Mich. (NewsNation Now) — A 15-year-old student opened fire at his Michigan high school Tuesday, killing four students and wounding at least seven other people including a teacher, authorities said.

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. Oakland County Sheriff Michael Bouchard said Tate died in a patrol car as a deputy tried to get him to a hospital. Shilling died Wednesday morning after being hospitalized in critical condition after the shooting.

Bouchard also said a teacher who received a graze wound to the shoulder was discharged from the hospital, but other students ranging in age from 14 to 17 remained hospitalized with gunshot wounds, including a 14-year-old girl who was on a ventilator after surgery.

Bouchard said Wednesday morning on “Morning in America” that investigators were still trying to determine a motive for the shooting at Oxford High School in Oxford Township, a community of about 22,000 people roughly 30 miles north of Detroit.

“The suspect is not talking to us at the direction of his parents,” said Bouchard. “In Michigan, the law requires juvenile get parental approval before he talks to the police and they refused it and have hired an attorney. So we’re not getting direct information on motive from the suspect.”

Bouchard spoke with “Morning in America” Wednesday morning. You can watch the full interview here.

The suspect’s father bought the 9mm Sig Sauer used in the shooting Friday, Bouchard said, adding that he did not know why the man bought the gun. Bouchard said the suspect had practiced shooting with the gun and posted pictures of it and the target.

Oakland County Undersheriff Mike McCabe earlier said he wasn’t aware of any prior threats.

“Please don’t believe everything you hear and see on social media,” McCabe said. “I’ve seen one screenshot of something about allegedly the shooter warning people not to come to school today but that was someone that got it from somebody.”

Authorities say they received more than 100 calls to 911 shortly before 1 p.m. about an attack.

17-year-old student Krista Hull said she heard the shots from her classroom.

“We didn’t even know what was going on because there was no P.A. announcement overheard,” Hull told NewsNation.

McCabe said deputies took the shooting suspect, who has not been identified, into custody without incident within minutes of arriving at the school.

McCabe also said the suspect’s parents visited him where he’s being held and advised their son not to talk to investigators, as is his right. Authorities executed a search warrant at his house.

Oakland County Prosecutor Karen McDonald issued a statement Tuesday evening saying her office expects to issue charges quickly and that an update would be given Wednesday.

The school was placed on lockdown, with some students sheltering in locked classrooms while officers searched the premises. They were later taken to a nearby Meijer grocery store to be picked up by their parents.

The district said in a statement that all of its schools would be closed for the rest of the week.

School administrators posted two letters to parents on the school’s website this month, saying they were responding to rumors of a threat against the school following a bizarre vandalism incident.

According to a Nov. 4 letter written by Principal Steve Wolf, someone threw a deer head into a courtyard from the school’s roof, painted several windows on the roof with red acrylic paint and used the same paint on the concrete near the school building.

Without specifically referencing that incident, a second post Nov. 12 assured: “There has been no threat to our building nor our students.”

“We are aware of the numerous rumors that have been circulating throughout our building this week. We understand that has created some concern for students and parents,” the administrators wrote. “Please know that we have reviewed every concern shared with us and investigated all information provided. Some rumors have evolved from an incident last week, while others do not appear to have any connection. Student interpretations of social media posts and false information have exacerbated the overall concern.”

Jeff Slotnick, an expert in security risk management, joined NewsNation Prime to talk about prevention.

This story is developing; check back for more information.

The Associated Press contributed to this report.