OXFORD TOWNSHIP, Mich. (WOOD) — A makeshift memorial to the four students killed in Tuesday’s shooting at Oxford High School is growing.

Gov. Gretchen Whitmer visited the school shortly before noon Thursday to add flowers to the site.

The shooting killed 14-year-old Hana St. Juliana, 16-year-old Tate Myer, 17-year-old Madisyn Baldwin and 17-year-old Justin Shilling.

Three students remain hospitalized following the shooting. Four other victims, including a teacher, have been released from the hospital.

Meanwhile fear from what happened in the halls of Oxford High School is spreading to other schools. More than two dozen school districts on the east side of the state closed Thursday because of copycat threats and fears from parents.

Investigators are sifting through evidence seized from the school and home of the suspected shooter, who is charged as an adult with two dozen crimes, including murder and terrorism causing death.

The 15-year-old’s father bought the 9mm Sig Sauger handgun last week.

The Oakland County prosecutor Karen McDonald said Thursday that the actions of the suspect’s parents “go far beyond negligence.” She told told WJR radio that the suspect’s parents didn’t do anything to lock up the gun used in the killings.

McDonald previously said the parents could face charges.