Three students have been killed after a 15-year-old sophomore opened fire at a Michigan high school on Tuesday, authorities said. The attack at Oxford High School in Oxford Township, roughly 30 miles (48 kilometers) north of Detroit, also left six people, including a teacher, wounded. Oakland County Undersheriff Mike McCabe said the motives of the assailant, who has been arrested, were not known. McCabe said investigators would be looking through social media posts for any evidence.

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Officers responded at around 12:55 p.m. to a flood of 911 calls about an active shooter at the school, McCabe said. Authorities arrested the suspect at the school and recovered a semi-automatic handgun and several clips.

“Deputies confronted him, he had the weapon on him, they took him into custody,” McCabe said at a news conference.

Officers responded at around 12:55 pm to multiple 911 calls about an active shooter at the school, McCabe said. Authorities arrested the suspect at the school and recovered a semi-automatic handgun and several clips.

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“Deputies confronted him, he had the weapon on him, they took him into custody,” McCabe said.

The suspect fired anywhere from 15 to 20 shots during the attack, McCabe added. 

“He didn’t give us any resistance when he was taken into custody,” McCabe said. “The whole thing lasted 5 minutes.” 

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Authorities didn’t immediately release the names of the suspect or victims.

Tim Throne, the superintendent of Oxford Community Schools, said he didn’t know yet know the victims’ names or whether their families had been contacted.

“I’m shocked. It’s devastating,” the shaken superintendent told reporters.

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The school was placed on lockdown after the attack, with some children sheltering in locked classrooms while officers searched the premises. They were later taken to a nearby Meijer grocery store to be picked up by their parents.

Robin Redding, the parent of a 12th-grader, said there had been rumblings of trouble at the school.

“He was not in school today. He just said that ‘Ma I don’t feel comfortable. None of the kids that we go to school with are going today,’” Redding said.

(With AP Inputs)