Four men were found dead in what appears to be a hit-style murder on Friday night.
The incident happened at a shack in Kuvo Street, Zwide at about 10.45pm.
While the motive is not yet known, police have not ruled out the possibility of a gang-related attack.
A 38-year-old woman was also shot in the arm.
Police spokesman Captain Andre Beetge said several spent cartridges were found on the scene.
"The discovery happened after the neighbour heard a loud quarrel erupting from a neighbouring shack. When she walked over to the shack to ask them to quieten down, several shots were fired inside the shack. She was wounded in her lower arm in the process but managed to run to safety," he said.
"On police arrival, four male bodies were discovered. Two inside and two outside. Several empty ammunition cartridges were found in and around the murder scene."
Beetge said only one of the victims had been identified - Bongani Yoni, 32.
"At this stage it is unknown what the reason for the murders or who the suspects are," he said.
Motherwell Cluster Commander, Major General Dawie Rabie said: "Crimes committed using firearms are a priority. We (SAPS) cannot allow these violent crimes and we urge our community to assist police in rooting out these criminals and their firearms."
Anybody with information is urged to contact Captain Jerome Mackay at the Motherwell Serious Violent Crime Unit on 076 018 0713.