Western Cape premier Helen Zille has asked President Jacob Zuma to deploy defence force members to gang-ridden areas, she said on Tuesday.
In a letter sent to the presidency on Monday, she asked for troops to be sent at once to Lavender Hill and Hanover Park on the Cape Flats, which had both seen a "serious spike" in gang-related deaths.
"While the SA police service have deployed extra resources to these areas, gang violence has continued unabated. It is clear that the current situation is beyond the capacity of the SAPS to control," she said.
"They need the support of the SA National Defence Force to restore order in these suburbs while they proceed with the task of investigative policing."
At least 23 people, including seven children, had died as a result of gangs in recent months.
In her letter, Zille said the deployment of the SANDF in gang hotspots over December had seen a marked improvement in safety levels.
Police Minister Nathi Mthethwa and Defence Minister Nosiviwe Mapisa-Nqakula were sent copies of the letter.
Some organisations however questioned Zille's plan. The Provincial Community Policing Forum Board told the Cape Times Zille had been "police-bashing" for the last two weeks, which showed gangsters that there was no unity.
"Police should not always be blamed. There are residents protecting gangsters. I don't think we are here to show the world we have bad policing, something Zille seemingly wants to show. It undermines policing in the country," chairman Hanif Loonat said.
The Institute for Security Studies was quoted in the newspaper as saying the army could be sent in only under exceptional circumstances, such as when public order broke down, or state security was threatened.
Senior researcher Johan Burger said provincial police should be dealing with the gangs. If they struggled, they should ask national police commissioner Riah Phiyega to have resources called in from other provinces.