A 15-year-old student at the Oxford High School in Michigan has shot at killed three students and injured seven others, including a teacher. The sophomore went into the school armed with a semiautomatic handgun and began shooting people on Tuesday afternoon.

The entire incident concluded in just five minutes after the shooter willingly surrendered to the responding police officers, who were nearby. He was reportedly unharmed and did not resist arrest.  Oakland County undersheriff, Michael McCabe, said they believed the student had worked alone. He added that they are still investigating the incident and are now interviewing other students and looking on social media to look for clues to a motive.

It is not yet clear if the student had randomly shot at people at the school or he had specifically targeted anyone. Some witnesses said he might have been bullied while he was attending the school.

A 16-year-old boy and two 14- and 17-year-old girls were among the three students who were killed during the school shooting. Two of the other victims were undergoing surgery Tuesday evening, while the remaining six are now reportedly in stable condition.

Although police stated that there were no warning indications, some parents and students said they had heard whispers that something horrible would happen at the school before Tuesday.

Oxford schools issued a letter to parents earlier this month informing them that "several rumors" had "circulated around our building this week" and that the school was looking into the issues.

Oxford High is a public high school in northern Oakland County that has around 1,800 students from Oxford, Oxford Township, and sections of Orion, Dryden, Metamora, and Addison townships.

Authorities said the first 911 call regarding the shooting came in at 12:51 p.m., and there were many more after that. More than 100 police officers and paramedics were dispatched. FBI agents also responded to the call.

Law enforcement officers encircled the school for most of Tuesday afternoon, helicopters hovered above the snow-covered parking lots, and frightened parents posted questions on social media to find out what was going on.

Reporters spoke with Oxford High School students who recounted a chaotic scene after a voice over the intercom announced an active shooter. Teachers immediately closed and locked doors, covered windows, and asked students to hide.  Those with cellphones texted their parents and friends to let them know what was going on.

Oakland County Sheriff's Office said they already have the suspect in custody and they have possession of the gun that was used in the shooting. Police said the suspect had already asked to see an attorney.