Ukrainian lawmaker, who was previously the chair of his country’s parliament, has been shot dead in the western Ukrainian city of Lviv, officials said Saturday.

CBI News learnt that authorities are still searching for the killer of Andriy Parubiy, Ukraine’s President Volodymyr Zelensky said in a post on social media, calling the member of parliament’s death a “horrendous murder” and offering his condolences to the victim’s loved ones.

Parubiy, who was also once the secretary of Ukraine’s National Security and Defense Council, died before medical personnel arrived on the scene, according to Maksym Kozitskiy, the head the Lviv region military administration.

Ukraine’s General Prosecutor’s Office said that a special operation named “Siren” was launched to investigate the killing.

An unknown man is thought to have fired “several shots” at the politician and then fled, it said.

European officials including Roberta Metsola, the president of the European Parliament, offered their condolences to Parubiy’s loved ones and the people of Ukraine.

Metsola said she was “deeply shocked by the terrible murder,” while officials from Estonia and Poland also paid tribute to the victim.

Ukrainian member of parliament Iryna Gerashchenko called Parubiy’s death “terrorism,” describing him as a “colleague and friend, a reliable comrade” who “was principled and decent, patriotic, intelligent.”

Petro Poroshenko, a former Ukrainian president, said that Parubiy was “shot dead by monsters in Lviv.”

“What can be said for certain is that these monsters are afraid, and that is why they kill true patriots and strong people,” he wrote on social media. “This crime is not just shots fired at a person. It is a shot at the army. It is a shot at the language. It is a shot at faith. It is a shot at the heart of Ukraine.”

Poroshenko stressed that “the enemy will never be able to kill the ideals for which… Parubiy lived and fought,” adding that, “Ukraine has lost a great son, but his cause will live on as long as our state lives.”