PARIS—The killing of a female police employee in a Paris commuter town on Friday was an attack on the French Republic, Prime Minister Jean Castex said on Saturday. The attacker, a French resident of Tunisian origin, stabbed the police administrative worker, a mother of two, at a police station in Rambouillet, just south of Paris. The attacker was shot dead by police. Authorities have not given a motive for the killing. President Emmanuel Macron said on Friday France had been the victim of a terrorist attack. “Once again, the Republic has been attacked. Once again, the French state has been threatened. We will not let this go by,” Castex said on Saturday, speaking to reporters from the southern city of Toulouse. BFM TV said Castex would hold a meeting later on Saturday in Paris with other government ministers. France’s anti-terrorism prosecutor said he was leading the investigation because the assailant …