Police estimate the shooting was conducted from a distance and at least two suspects have already been arrested on suspicion of being involved in the incident.
Lapid, who was the conference hall when the shooting happened, said the incident will not “deter or intimidate” the party.
“We will continue to fight for changes in this country in the face of violence and incitement."
Blue and White Chairman Benny Gantz toured the predominantly Bedouin city of Rahat in southern Israel earlier on Thursday, where he criticized the political agreement between Prime Minister Benjamin Netanyahu’s Likud and Moshe Feiglin’s Zehut.
“Feiglin talks about personal freedom, but Netanyahu talks about his personal freedom,” he said. “We see an extremist alliance holding hands."