A Ukrainian former lawmaker best known for her crusade to promote the Ukrainian language has died after being shot in the street by an unknown assailant.

Iryna Farion, 60, initially survived the assault in the western city of Lviv on Friday, but later died from her wounds in a hospital. A search is underway for her attacker, who fled from the scene. Ukrainian officials said that an investigation is being carried out and that the attack is being treated as an assassination.

“All available surveillance cameras are being worked on, witness interviews are ongoing, and several districts are being surveyed. All leads are being investigated, including the one that leads to Russia,” Ukrainian President Volodymyr Zelenskyy said on his official Telegram channel Saturday.

“All necessary forces from the National Police of Ukraine and the Ukrainian Security Service have been deployed to search for the criminal.”

Farion served as a member of the Ukrainian parliament between 2012 and 2014 — and was best known for her campaigns to promote the use of the Ukrainian language by Ukrainian officials who spoke Russian. She controversially criticized Russian-speaking members of Ukraine’s Azov regiment who defended the port city of Mariupol in the first days of the full-scale invasion.

Police are considering “personal animosity” toward the former MP due to her social and political activities as a likely motive behind the attack, said Interior Minister Ihor Klymenko, who will oversee the investigation in Lviv.