The shooter then walked out of his house and killed another 7 people. In a shootout with the police, a policeman was injured, Brdjanin said.
"When we arrived at the scene we saw nine dead bodies, including two children, and another two passed away on their way to the hospital," Andrijana Nastic, a state prosecutor, told Vijesti TV.
"I can only say that the shooter was killed by a citizen (civilian)," Nastic said. Earlier, media reported that police had killed the shooter.
Montenegro's Prime Minister Dritan Abazovic said a three-day mourning period would be declared in the country starting Friday evening.
"I was deeply disturbed with reports about terrible tragedy in Cetinje. I express my deepest condolences to those families affected and all those who lost their loved ones," President Milo Djukanovic tweeted.