Moscow — At least eight people were killed on Tuesday in a shooting attack at a high school in the central Russian city of Kazan, Russian officials said. The press service of the President of Tatarstan, of which Kazan is the capital, confirmed that at least four male and three female students, and a female teacher, were killed. The regional president’s office said 21 people were injured, 18 of them students and six of whom were in intensive care. “The terrorist has been arrested, (he is) 19 years old. A firearm is registered in his name,” Tatarstan governor Rustam Minnikhanov told reporters after visiting the scene. “Other accomplices haven’t been established, an investigation is underway.” According to Tatarstan health officials, 21 people were hospitalized with wounds after the attack, including 18 children, six of whom were in intensive care. Video posted to social media showed at least two people falling or jumping from a third-floor window of the School No. 175 building, which was said to have about 700 students in attendance on Tuesday when the shooting started. Authorities restricted entry to all schools and toughened security measures at educational institutions in Kazan after the gunmen opened fire on Tuesday, the city’s mayor’s office said. Kazan is the capital of Russia’s Tatarstan region, about 434 miles east of the capital, Moscow.