Mayor is Jewish. My guess is this is another Russian attempt to paint the Ukrainian government in a bad light.
There were reports a couple days ago he was being “uncooperative” and the separatist vote wasn’t going to happen in Kharkiv on May 11. This assasination attemption fits in with a general escalation by Team KGB today across the region. There were shootings, IED assault, peaceful marchers attacked, etc. This is about to kickoff.