German police said Saturday they had no evidence a teenage gunman who killed nine people in Munich had any links to the Islamic State group and described the attack as “a classic act by a deranged person.”

“There is absolutely no link to the Islamic State,” Munich police chief Hubertus Andrae said, adding that the suspect had been obsessed with books and articles about mass killings “linked to maniacs.”

The Munich prosecutor also said the suspect — whose name has been withheld for the time being — had suffered depression and reportedly undergone psychiatric treatment.