His mother's head was "completely separated from her body." His father, wounded, ran to the neighbors for help.
Violence erupted between a white supremacist group and counter protesters at demonstration at the state capital.
The alleged assailant, a 27-year-old man who was under arrest and suspected of using drugs, shouted "Allahu Akbar" ('God is Greatest' in Arabic).
Police have released five Ku Klux Klan members arrested after a Saturday rally turned into a bloody brawl, saying that the Klansmen acted in self-defense.
The killing came amid tighter border controls in Sweden to curb the influx of refugees to the country.
Two of the stabbing victims were flown out by medical helicopter and three were treated on campus.
Mark Costello was stabbed multiple times in the head and neck, and later died at a hospital from his injuries on Sunday night.
A blogger was hacked to death by machete-wielding attackers in Bangladesh on Tuesday, the third killing of an online critic of religious extremism in the Muslim-majority nation in less than three months.
The killing comes weeks after a U.S. secular blogger was hacked to death in the city.
Police shot a man after he stabbed a 22-year-old Israeli student in the head.