A 17-year-old boy has become the fourth person to die in the shooting at a high school in Oxford, Michigan on Tuesday afternoon, NBC News reports.
Justin Shilling succumbed to his injuries at approximately 10:45 AM - a day after the shooting at McLaren Oakland Hospital in Pontiac, the Oakland County Sheriff's Office said.
Police had previously identified three victims who died in the shooting as Hana St. Juliana, 14; Madisyn Baldwin, 17; and Tate Myre, 16.
Seven others sustained serious injuries and were treated at hospitals, including a teacher, Sheriff Michael Bouchard said. Three of those wounded in the attack were discharged on Wednesday, and two teenage students remain in serious condition.
The shooting took place not long before 1 PM. According to police, there were more than a hundred emergency calls about the carnage.
The 15-year-old suspect has now been identified as Ethan Crumbley. The teen was taken into custody and charged with four counts of first-degree murder, one count of terrorism causing death, seven counts of assault with intent to murder, and 12 counts of possession of a firearm in the commission of a felony.
He is being charged as an adult and was arraigned on Wednesday.
Oakland County Prosecutor Karen McDonald said at a news conference that the attack was planned as opposed to being an "impulsive act."
She said: "There is a mountain of digital evidence — videotape, social media, all digital evidence possible — and it absolutely, we are confident that we can show it was premeditation."
According to police, Crumbley started shooting after leaving a bathroom at the school. He remained in the hallway until police arrived at the scene and arrested him.
Undersheriff Michael McCabe stated that the youngster was in custody within five minutes of the arrival of officials. The 15-year-old had been denied bond and is to be transferred to the Oakland County Jail, where he will remain isolated from other inmates.
During the news conference, McDonald spoke in detail about how those present at the time of the ordeal reacted to the shooting
"When the shooting started yesterday, the students and teachers and staff in the school had to act quickly to save their own lives," she said. "Law enforcement and all of the first responders had to act quickly to prevent more lives from being lost and get help for those who had been shot."