At least eight died in Kazan, a city in Russia, after a school shooting including seven children and a teacher. 

Local authorities said a 19-year-old active shooter has been detained from the school. The firing began while hundreds of children were inside classes.

"It's a great tragedy. We have lost seven children, four boys, three girls. They died here on the third floor," Tatarstan's president, Rustam Minnikhanov told reporters standing outside the school following the shooting.

According to Russian media 18 more children have been hospitalized after the shooting, six of whom are in critical condition.

Russia's Investigative Committee has said it has opened a criminal case into the shooting and that according to preliminary information the alleged 19-year-old gunman entered the school alone.