Oxford, Michigan - A 15-year-old boy opened fire and killed at least three students at his high school in Oxford, Michigan, seriously injuring another eight people.

Oxford High School students Tate Myre (16), Hana St. Juliana (14), and Madisyn Baldwin (17) were killed in the horrific attack on Tuesday afternoon, Oakland County Sheriff Michael Bouchard confirmed. Of the eight injured people, one is a teacher, while the others are students.

The alleged perpetrator, who goes to the same school, was disarmed at the scene after firing 15 to 20 shots in five minutes, just before 1 PM local time. Police said he did not resist arrest.

The 15-year-old didn't make any statements about a motive and was later advised by his parents not to speak until his lawyer was present.

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In a chilling twist, it emerged that ominous rumors of a potential shooting had been swirling around the school for a while. The Guardian quoted the mother of a student who stayed home on Tuesday due to threats he had been hearing "for a long time now."

Undersheriff Michael McCabe denied having any knowledge of this and said no reports were ever made.

President Joe Biden tweeted his condolences to the families of the victims: "My heart goes out to the families of all those in Oxford, Michigan experiencing the unimaginable grief of losing a loved one. I'm remaining in close touch with my team as new information about this tragic school shooting surfaces."

Michigan Governor Gretchen Whitmer also reacted on Twitter, writing: "I’m devastated for the students, teachers, staff, and families of Oxford High School. The death of multiple students and shooting of others, including a teacher, is horrific."

According to Education Week, which has been covering K-12 since 1981, this was the 28th school shooting in 2021, almost three times as many as the previous year. The vast majority – 20 – have taken place since August 1 and overall, 57 people have been killed or injured.

Meanwhile, Biden's gun control agenda continues to languish in Congress, where no meaningful measures have much chance of being passed, given the Democrats' paper-thin Senate majority and united Republican opposition.

A fourth high school student, 17-year-old Justin Shilling, died on Wednesday after succumbing to injuries, according to reports. Several other victims remain in critical condition.

The 15-year-old suspect has been identified as Ethan Crumbley and is being charged as an adult with one count of terrorism causing death, four counts of first-degree murder, seven counts of assault with intent to murder, and 12 counts of possession of a firearm during the commission of a felony, Oakland County Prosecutor Karen D. McDonald said Wednesday. He is being held in a juvenile jail.

The weapon used in the shooting was a pistol reportedly purchased by the suspect's father just days before on Friday, the sheriff said. Mcdonald confirmed prosecutors are also considering bringing charges against Crumbley’s parents.

Authorities also believe that the shooting was planned "well before the incident" and are investigating pictures of a target and the weapon posted on social media by Crumbly. They also are examining his cell phone, computer, and writings to uncover a motive.

Crumbley pleaded not guilty at his arraignment, held Wednesday afternoon, via video from his detention facility.

It has been revealed that his parents, Jennifer and James Crumbley, had a meeting at his school over their son's behavior in the classroom just three hours before the shooting.

Crumbley himself had also been spoken to by school officials about his "concerning behavior" the previous day.

Investigators have recovered journal entries and two videos from the suspect's cellphone, made the night before the incident, where he discussed killing students at Oxford High.