ROME-- Italy has condemned the terror attack at a suburban Moscow concert hall and stepped up security at key transportation, cultural, and religious sites across the country.

The terror attack on Friday killed at least 133 people and injured over 100, the Investigative Committee of Russia said Saturday.

Calling the attack "the massacre of innocent civilians," Italian Prime Minister Giorgia Meloni said "the Italian government firmly and totally condemns this brutal act of terrorism."

In a statement, Italian President Sergio Mattarella said the world stands united behind the victims of the attack, calling on the international community to fight terrorism.

Italy's Ministry of the Interior said on Saturday that it has ordered the security level at "sensitive" sites to be raised in Rome and other cities, including airports, train stations, as well as key cultural and religious sites.

The ministry also said that it will hold a special meeting on Monday to analyze potential risks after the Moscow attack.