JERUSALEM—A knife-wielding Arab man on Tuesday killed four people and seriously wounded two others in the southern Israeli city of Beersheba before he was killed by armed residents, police said. Police said the attacker careened his car into a cyclist and stabbed five people across a swath of the city center. Amateur video footage posted online appeared to show armed bystanders shooting and killing the attacker at the scene. Israel Police chief Kobi Shabtai told reporters at a press briefing at the scene that the incident was “an abominable killing spree by a terrorist known to security services” who had previously served prison time. He said that the attacker appeared to have acted alone. Shabtai declined to comment further on the suspect. But Israeli media identified the attacker as a 34-year-old Arab man from the nearby Bedouin town of Hura. Reports said he was imprisoned for four years after admitting …