Other than the 12 killed, at least four others were wounded in the shooting, which occured after a bar brawl in Cetinje on Wednesday, officials said.
The shooter, identified as 45-year-old Aco Martinović, killed the owner of the bar and his two children as well as some customers, before moving on to other locations and shooting several other people, including family members of his.
The attacker tried to flee but was later found by police, who said he died after shooting himself.
This was the second such incident in the town in the past three years.
