Seven people were killed when gunmen went on a shooting spree in Goma, a major city in the troubled east of the Democratic Republic of Congo, the mayor said Monday."Some unidentified men spread terror" late Sunday in Goma, mayor Thimotee Muissa Kense told AFP."They were shooting in all directions," he said, immediately killing three people and wounding 22 others."Four people later died of their wounds. Eighteen others are still in hospital," the mayor said.A 33-year-old butcher who witnessed the shooting told AFP that on Sunday evening two people arrived on a motorcycle in the neighbourhood of Mugunga on the outskirts of Goma."They opened fire on people. Three people died, and there was panic. We hid ourselves in a kiosk," the witness said.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and FacebookA security source speculated that it could have been a settling of scores by a armed group from the neighbouring Masisi territory against a man, his wife and their child.Located on Lake Kivu at the border with Rwanda, Goma is the capital of North Kivu province with a population of around one million. Gun attacks inside the city is rare as it is a headquarters of the UN mission in DRC known as Monusco. There have been crimes reported in recent months in Goma including the kidnapping of children for ransom, and violence followed by the killing of the young hostages.North and South Kivu provinces have for decades been the theatre of a wave of violence among militia groups, which often extort money from civilians or fight each other for control of mineral resources.