Three students have been killed and eight others injured, including a teacher, in a high school shooting in the US state of Michigan.
The dead include a 16-year-old boy, a 14-year-old girl and a 17-year-old girl, officials say.
Police say the 15-year-old suspect fired 15 to 20 shots with a semi-automatic handgun and acted alone.
The assailant’s motives for the attack in the town of Oxford, about 40 miles (65km) from Detroit, remain unclear.
Oakland County Undersheriff Mike McCabe told reporters at a news conference outside the Oxford High School on Tuesday that calls to emergency services began at 12:51 local time (17:51GMT).
Within minutes, officials had received 100 calls to 911, he said.
Officials say the suspect, a second-year male student, surrendered five minutes after police were called.
A police officer stationed at the school helped to arrest the suspect, he said. No shots were fired during the arrest, and the teenager was not injured.
“He gave up without any problems,” said Mr McCabe, who later added that the suspect had been in class before the shooting began.
The school was evacuated, and officials conducted three separate sweeps of the campus to ensure that there were no additional victims.
Two of the injured were undergoing surgery, while the other six were in a stable condition with gunshot wounds.
In the news conference, officials said the suspect had so far refused to speak and was “not co-operating”.
He added that the suspect had been told by his parents not to talk to police and that a search was being conducted of the pupil’s home.
He added that the suspect was not wearing body armour during the shooting, and that officials know how the gun was brought into the school, but are not yet able to reveal that detail.
“Of course I’m shocked. I’m devastated,” said Oxford Superintendent of Schools Tim Throne.
It has not yet been decided whether classes will resume on Wednesday, according to Mr Throne.
President Joe Biden spoke about the shooting during a visit to Minneapolis, Minnesota.
“My heart goes out to the families enduring the unimaginable grief of losing a loved one,” he said.
Michigan Governor Gretchen Whitmer described school shootings as “a uniquely American problem that we need to address”.
US shootings on school grounds have been ticking steadily upwards in recent years, according to pro-gun control group Everytown.
After a brief dip last year during coronavirus lockdowns, the number of such attacks has rebounded with 138 incidents of gunfire on school grounds so far in 2021.