Austria has tightened security at churches amid warnings of copycat attacks in the wake of the deadly shooting rampage in Vienna earlier this month. Interior Minister Karl Nehammer said preliminary findings from the investigation into the November 3 shooting found that the attacker was planning to target places of worship. The terrorist, Kujtim Fejzulai, a 20-year-old ISIS sympathiser who was born and raised in Vienna, was shot dead by police after firing on members of the public on the final night before Austria entered its second lockdown. Four people were shot dead. Austria is investigating 21 people and has remanded 10 in custody on suspicion of being connected to the attack. Mr Nehammer said: “The investigation's findings currently show that it cannot be ruled out that the perpetrator also wanted to deliberately seek out victims in churches. “There will therefore be a reinforced protection of church facilities as of today.” He added that his aim was to guard against copycat attacks in the “sensitive phase” following Fejzulai’s rampage in the run-up to Christmas. The warning came as a rabbi was attacked at knifepoint in Vienna by a woman who ripped the Jewish skullcap from his head and yelled an anti-Semitic threat before fleeing. Police said the woman, who has not been found, approached the rabbi and pulled a knife from her handbag. Mr Nehammer condemned the incident as an “attack on Jewish life in Vienna”. Austrian authorities have admitted "intolerable mistakes" were made in the handling of intelligence on Fejzulai, which included his attempt to buy ammunition in Slovakia and a meeting in Vienna with known foreign extremists. Investigators said the attacker, who was released early from jail, should have been considered a greater threat and monitored more closely. Fejzulai had been convicted of trying to travel to Syria to fight for ISIS, for which he was jailed in April 2019. Authorities said he managed to “trick” officials into believing he had been deracialised.