At least nine people were killed in a shooting at a school in the Russian city of Kazan, officials say.
Twenty one other people, mostly children, were injured. A 19-year-old suspect was detained.
The attack happened in the capital of the republic of Tatarstan, 820km east of Moscow.
Russian PM Mikhail Mishustin spoke of “great sorrow” while Tatarstan’s leader Rustam Minnikhanov described the attack as a “major tragedy”.
“We are deeply saddened that this has happened,” he said.
Mr Minnikhanov confirmed the deaths of seven children – four boys and three girls – as well as a teacher and a female school worker at School No 175. It is believed the children were eighth graders.
Eighteen children and three adults were being treated in hospitals for gunshot wounds, fractures and bruising, Mr Minnikhanov added.
The attack began at about 09:20 local time. Heavily armed police and emergency vehicles responded to the incident.
Reports initially said that there were two gunmen and that one of them had been killed. But officials later said there was only one suspect, named locally as Ilnaz Galyaviev.
Russian investigators say he is a Kazan resident and it is believed he once studied at the school.
Mr Minnikhanov said the suspect was a registered firearm owner. According to Russian MP Alexander Khinshteyn, the suspect received a firearms licence only recently, saying it was for a semi-automatic shotgun.
Officials did not comment on the possible motive for the attack although Mr Minnikhanov called the attacker a “terrorist”.
The suspect went on social media before the attack, posting that he planned to kill a “huge number” of people before shooting himself. Screenshots of his account, now blocked, show him wearing a black mask with the word “god” written across it in red.
Responding to the shooting, Russian President Vladimir Putin said he would review the country’s gun control laws
School shootings are relatively rare in Russia. One of the last major incidents happened in Russian-annexed Crimea in 2018.