Footage of the suspected shooter showed an individual dressed in black walking on one of the school’s sidewalks and holding a long-barreled firearm. Russia’s Investigative Committee, the main federal investigation authority in the country, said that the suspected shooter fired a smoothbore hunting gun, which could mean that he used a shotgun in the attack, AP reported.

Gun laws are strict in Russia, but many residents are still able to procure permits for hunting. Authorities said the suspect was a student at Perm State University but did not provide his identity or any information on a motive.

For more reporting from the Associated Press, see below.

During the attack, students and staff at the university locked themselves in rooms, and video posted on Russian news sites showed some students jumping out of second-story windows.

The university, which has 12,000 students, said about 3,000 people were on campus at the time of the shooting. The school is in Perm, a city 1,100 kilometers (700 miles) east of Moscow with a population of about 1 million.

The Investigative Committee said some of the 28 people who were injured were hospitalized. The Health Ministry said 19 of them were shot; it was not clear how the others were injured.

In a video released by the Interior Ministry, a witness whose name was not given said he saw the man outside after shooting two people and that he appeared to be wearing a bulletproof vest.

A traffic police unit was the first to reach the scene, and the suspect opened fire on them, according to the Interior Ministry. He was wounded when police returned fire and then was disarmed. The gunman also was armed with a knife, the ministry said.

One traffic officer said people were rushing out of the university building as gunshots were heard.

“I entered the building and saw an armed young man walking down the stairs. I shouted at him ‘Drop it!’” That’s when he pointed the gun at me and fired. At that point I used my gun," Officer Konstantin Kalinin said in the ministry video.

School shootings are infrequent in Russia, but the Perm attack was the third in recent years. In May, a gunman opened fire at a school in the city of Kazan, killing seven students and two teachers with a registered weapon. A student at a college in Russia-annexed Crimea killed 20 students and himself in 2018.

After the Kazan shooting, President Vladimir Putin called on the national guard to tighten gun regulations. Russia then passed a law raising the minimum purchase age from 18 to 21.

The Russian leader offered his condolences on Monday.

“It is a tremendous tragedy, not only for the families who lost their children but for the entire country,” Putin said.