Three students were confirmed dead hours after the shooting at Oxford High School on Tuesday: Tate Myre, 16; Madisyn Baldwin, 17; and 14-year-old Hana St Juliana.
A fourth student, 17-year-old Justin Shilling, succumbed to injuries in a hospital on Wednesday.
Six other students, aged between 14 and 17, remain hospitalised with gunshot wounds, including a 14-year-old girl on ventilator after undergoing surgery. A teacher who suffered a graze wound to the shoulder was discharged from hospital.
The suspected shooter was identified on Wednesday as 15-year-old sophomore Ethan Crumbley. He is facing a slew of charges, including terrorism and first-degree murder.
Tate Myre, 16
Footballer Myre died in a patrol car as a deputy tried to get him to a hospital, Oakland County Sheriff Michael Bouchard said.
The gunshot wounds were so grievous that there was no time to wait for an ambulance, the sheriff said. “This wound will never go away,” he added.
Myre was part of the Oxford High School junior football team.
“It is with great grief that one of the victims of the tragic events at OHS today was one of our own, Tate Myre. Tate was on varsity since his freshman year and was an honour student. Tate was a great young man with a bright future and beloved by all,” the football team wrote on their Facebook page.
Madisyn Baldwin, 17
Baldwin’s grandmother, Jennifer Graves Mosqueda, confirmed her death in a heartbreaking Facebook post with a GoFundMe campaign link on Tuesday evening.
“This beautiful, smart, sweet loving girl was tragically taken from us all today leaving a huge hole in all of our hearts and lives,” she wrote.
“This horrific day could never have been imagined or planned for. My daughter and son-in-law would never ask for anything during this time, however, I want them to be able to be with each other, their other children and family during this time without worrying about work, bills and arrangements.”
Hana St Juliana, 14
The youngest person to die in Tuesday’s shooting was 14-year-old St Juliana, a freshman at the school.
She played on the school’s volleyball and basketball teams.
The basketball team posted a touching tribute to her on Twitter, writing: “We will never forget your kind heart, silly personality, and passion for the game. Since 6th grade camp you have stayed dedicated to Oxford Basketball, soaking in the game… This season, we play for you Hana.”
Justin Shilling, 17
Shilling died at a hospital on Wednesday morning. He was described as a passionate member of Oxford High School’s bowling team.
Mr Crumbley was taken into custody for opening fire at the school in Oxford Township, a community of about 22,000 people that is located roughly 48km north of Detroit.
“There was no resistance during the arrest and the suspect has asked for a lawyer and has not made any statements as to a motive,” the sheriff’s office said.
A semi-automatic handgun and several clips were recovered from Mr Crumbley. His father bought the 9mm Sig Sauer pistol on 26 November from which 15-20 shots were fired inside the school, authorities said.
On Tuesday evening, law enforcement seized several guns from the suspect’s family home on East Street near the school.
Threats of a shooting allegedly circulated on the high school campus prior to Tuesday’s fatal rampage.
Robin Redding, the mother of 12th grader Treshan Bryant, told the Associated Press that her son opted to stay home on that unfortunate day because he and his younger cousins had a “bad feeling” that violence could be coming.
Treshan said he had heard vague threats about plans for a shooting “for a long time now”.
President Joe Biden offered his sympathies to the victims’ families. “As we learn the full details, my heart goes out to the families enduring the unimaginable grief of losing a loved one. You’ve gotta know that that whole community has to be just in a state of shock right now (sic),” the president said.
Meanwhile, a fundraiser has been created on GoFundMe for the victims.