One of Paris' busiest tourist areas turned into a nightmare zone on Thursday,... as four people were brutally stabbed to death in the French capital's police headquarters.br Police say a 45-year-old IT assistant went on a knife rampage inside the building, killing three officers and an administrator.br Three of the victims were men, one was a woman.br The attacker was eventually shot dead by an officer.br Police didn't immediately specify the motive, but investigators told reporters it may have been sparked by a personal conflict.