Nineteen people were killed and dozens more wounded, most of them teenagers, after a student opened fire in a technical college in Russian-annexed Crimea on Wednesday, the authorities said.
The toll rose to 19 on Wednesday afternoon, regional medical officials told TASS state news agency.
They said 39 remained hospitalised after the attack on the college in the city of Kerch on the peninsula annexed from Ukraine in 2014.
Russia's Investigative Committee said the attack was carried out by 18-year-old student Vladislav Roslyakov.
He was captured on security camera footage and later found dead with gunshot wounds.
Roslyakov enrolled at the college in 2015, according to its website.
RBK newspaper quoted an anonmyous fellow student as saying Roslyakov "really hated the college because of evil teachers and hinted he would take revenge on them."
Violent attacks on schools and colleges are extremely rare in Russia but there have been several high-profile cases recently with far fewer victims.
The Investigative Committee, which probes major incidents, had initially classified the attack as an act of terror and described it as an explosion.
But it later said it was investigating a mass murder after "this young man shot people dead in the college and then committed suicide," adding that all the victims died of gunshot wounds.
The attack had first been reported as an explosion and the Russia's National Anti-Terrorism Committee said an "unidentified explosive device" had gone off in the canteen.
Committee spokesman Andrei Przhezdomsky said that Roslyakov's body was found next to a pump-action gun.
Crimean leader Sergei Aksyonov told Russian television: "It was a mass murder committed by one scumbag."
The reported killer was a "student in the fourth year who was studying at the college. His body was found in the college library," Aksyonov wrote on Facebook.
A source in the emergency services told RIA Novosti state news agency that Roslyakov had legally acquired a gun licence.
The Investigative Committee said most of the victims were teenagers. The college's website says it accepts students in the last three grades of school, from the age of 14.
The regional health ministry said six of the injured were in an extremely serious condition and eight in a serious condition.
Aksyonov announced three days of mourning from Thursday over the "terrible tragedy".
Russian President Vladimir Putin, who was in the Black Sea resort of Sochi, said in televised comments that a "tragic event" had happened, speaking during talks with Egyptian President Abdel Fattah al-Sisi.
"It's already clear that it's a crime, the motive and possible versions for this tragedy are being carefully examined," Putin said.
"I want to express condolences to the relatives of the dead and express the hope that the injured recover as quickly as possible," the president said, calling for a minute's silence to mourn the victims.
Kerch is linked to the Russian mainland by a bridge that Putin opened in May.
Witnesses said that the attacker fired shots but also spoke of hearing an explosion.
A student at the college who asked not to be named told AFP: "I was in a class when I heard shooting on the first floor."
"When we all ran out into the corridor, there were others running and shouting that some guy with a machine gun was randomly shooting everyone in turn."
"Then a strong explosion went off, but thank God, I was already outside and saw our guys being thrown out of the windows by the explosive wave," he said, adding that part of the building collapsed.
Another witness who gave his name as Sergei and who worked nearby said in a video on the Kerch.tv website that he heard "a bang and shots."
Sergei, whose shirt was covered in blood, said victims "were taken away in public transport, in minibuses and buses, with two or three people in each ambulance."
"They are children and staff," the witness said. "I saw people without legs, without arms."
Attacks by disaffected teenagers at their schools and colleges have hit the headlines recently in Russia.
In January, a school student attacked a teacher and fellow students with an axe in Siberia and tried to set fire to the school building and to kill himself.
In April, a school student stabbed a teacher and a fellow student in the Urals Mountains and then set fire to a classroom.