At least nine people, eight of them children, have been killed by gunfire at a school in the Russian city of Kazan, reports say.
A teacher also died in the incident 820 km (510 miles) east of Moscow.
Two people reportedly opened fire and a 17-year-old boy is said to have been detained.
An explosion was heard, and it was unclear what had happened to the second attacker. Kazan is in the mainly Muslim Republic of Tatarstan.
Heavily armed police and emergency vehicles were seen outside the school, and amateur video on social media showed some children jumping from windows to escape as well as injured people being evacuated.
One video on social media captured a teenager lying on the ground apparently being detained outside the building.