WUERZBURG, Germany–Authorities in Germany were investigating on Saturday what prompted a man to go on a rampage with a knife in the town of Wuerzburg on Friday, killing three women and seriously injuring five other women. Officials said the suspect, whose rampage was halted when police arrested him, was a 24-year-old Somali immigrant who had had mental health problems in the past. As is the practice in Germany, they did not name him. Officials assume the suspect was acting alone, but are still investigating whether there was any Islamist motive for the attack, regional Interior Minister Joachim Herrmann told a news conference. Herrmann cited one witness as saying that before starting his spree, the suspect had shouted “Allahu akbar,” an Arabic phrase that means “God is great” and that is often associated with acts of Islamist militancy when used by attackers. “The indications of radicalization, in this case Islamism, and …