Dramatic video shared on social media shows students fleeing a classroom after fearing a shooter in a deadly attack at a Michigan high school was at the door, trying to lure them out.
Three students were killed and eight others injured in the shooting at Oxford High School in suburban Detroit on Tuesday, authorities have said. A suspect, a 15-year-old sophomore, has been taken into custody.
In the video, which was shared to TikTok shortly after the incident, several students can be seen huddled in a classroom with the lights off as they hear a voice at the door.
"Sheriff's office. It's safe to come out," the voice calls.
Someone in the classroom responds: "We're not willing to take that risk right now!"
It is not known who was at the door of the classroom. Authorities did not immediately respond to a request for information early Wednesday morning.
When the person outside the classroom asks them to "come to the door and look at my badge, bro," other students appear to panic, calling their use of the word "bro" a "red flag."
The students then start to rush toward a window in the classroom, with one student urging others to "go, go, go" as others can be heard crying.
The students can then be seen jumping out the window and running into the snow towards a separate building entrance, where a law enforcement officer ushers them in, telling them "slow down, you'e fine."
Students Hana St. Juliana, 14, and Madisyn Baldwin, 17, were killed in the shooting. Tate Myre, 16, died in a patrol car as deputies rushed him to the hospital, the Oakland County Sheriff’s Office said late Tuesday.
The eight who were injured in the attack, including a teacher, were seriously wounded and taken to hospital for various injuries, Oakland County Sheriff Michael Bouchard said.
At least three of the wounded students were in critical condition late Tuesday night, including a 15-year-old boy with a gunshot wound to the head and a 14-year-old girl who was wounded in the neck and chest and was put on a ventilator, he said.
Law enforcement had been alerted to the incident after receiving a 911 call about an active shooter at the school just before 1p.m., Oakland County Undersheriff Michael McCabe told reporters after the incident.
He said authorities received more than a hundred 911 calls about the incident.
“Deputies responded and within five minutes had the suspect in custody,” McCabe said.
The undersheriff added that the suspect “did not cause any problems. He gave the weapon up. He didn’t have the weapon on him at the time.”
McCabe said the suspect had “invoked his right not to speak,” adding that police had spoken with the suspect’s parents, who he said had advised their son not to speak to law enforcement.
Authorities learned in the aftermath of the shooting that the handgun believed to have been used in the attack, a 9mm Sig Sauer, had been purchased by the suspect’s father on Friday, just days before the incident, the Oakland County Sheriff’s Office has said.
They said it was unclear why the father had bought the handgun.
“The person that’s got the most insight of the motive is not talking,” Bouchard said, calling the deadly attack an “unspeakable and unforgivable event.”
In a statement published on Facebook overnight, the sheriff said that after a “detailed walk-through and examination” of the scene it was “evident” that “the lockdown protocols, training and equipment Oxford schools had in place saved lives.”
He also said his "heart aches for families that will never be the same and a quiet sweet community that had its innocence shattered."
A version of this story originally appeared on NBCNews.com.