KIEV, Oct. 17 (Xinhua) -- At least 19 people, mostly teenagers, were killed and 40 others were injured Wednesday in an attack on a college in the city of Kerch in Crimea, local media reported.

According to the reports, an unknown explosive device went off in a canteen of the Kerch Polytechnic College around midday local time (GMT 0900). The blast was accompanied by shooting.

The Ukrainian Prosecutor's Office of Crimea and the Russian Investigative Committee have opened separate criminal investigations into the incident on charges of a "terrorist act."

Later in the day, the Russian Investigative Committee said the case was a "mass murder" and named 18-year-old Vladislav Roslyakov as a suspected shooter.

Roslyakov, the fourth-year student of the college, has committed suicide after the attack, the committee said in a statement.

Eyewitnesses told local media that there were several attackers, but those reports have not been officially confirmed.

The state of emergency was imposed in Kerch in the wake the attack. All educational establishments in the city are d.

The three-day mourning for the victims of the attack was declared in Crimea.

Crimea was incorporated into Russia in March 2014 following a local referendum. Ukraine says the peninsula was annexed.