A former secretary of the National Security and Defense Council of Ukraine was shot and killed Saturday in the city of Lviv, while authorities continued the search for the killer.

President Volodymyr Zelensky confirmed the death of Andriy Parubiy in a post on X, adding that "All necessary forces and means are engaged in the investigation and search for the killer."

Authorities are searching for one man who reportedly fired "several shots" at Parubiy Saturday afternoon in the largest city in Western Ukraine.

Zelensky said Ukraine's Minister of Internal Affairs and Prosecutor General informed him of the "horrendous murder," while also offering condolences to the 54-year-old's family.

The National Police of Ukraine is involved in the search for the suspect, with Ukraine's General Prosecutor's Office launching a special operation to find the killer.

Parubiy also previously served as speaker of the Ukrainian parliament where he was outspoken against Russian influence, accusing that country and then President Dmitry Medvedev of trying to interfere in Ukraine's elections.

While working as secretary of Ukraine's national security agency in 2014, Parubiy asked the United Nations to intervene after pro-Russian activists took control by force of a Ukrainian naval base in the city of Sevastopol in the Crimean region.