Minnikhanov's press service later said that a teacher was also killed. "Other accomplices haven't been established, an investigation is underway", Minnikhanov said after visiting the school, noting that security had been restored to the school.
Two children could be seen leaping from the third floor of the four-storey School Number 175 as gunshots sounded, in a video filmed by an onlooker that was circulated by RIA.
News agencies reported that one shooter, a 17-year-old, had been detained.
The regional prosecutor's office in the republic of Tatarstan said it has begun looking into the shooting and the regional prosecutor has been deployed to the scene.More news: Man shot to death at Vancouver airport was subject of public warning
Footage of the school building showed dozens of ambulances lined up in front of the entrance.
Local media reported that two unidentified attackers opened fire at the school in the Russian city of Kazan.
While school shootings are relatively rare in Russian Federation, there have been several violent attacks on schools in recent years, mostly by students.
The shooting took place in Kazan, roughly 700km east of Moscow.
In October 2018, a teenage gunman killed 20 people at the Kerch technical college in Crimea, the peninsula Russian Federation annexed from Ukraine in 2014.More news: New York Times Square shooting leaves three injured, including a child
"The terrorist has been arrested, [he is] 19 years old".
Responding to the attack, Russian President Vladimir Putin said he would review Russia's gun control laws.
He was shown in camera footage wearing a similar T-shirt to Eric Harris, one of the killers in the 1999 Columbine High School shooting in the USA, which left 13 people dead.
The source added that preliminary information indicated one of the shooters was a teenager, who has been detained.More news: Boris Johnson hails Conservatives' crushing win in U.K. Labour stronghold