Two men were taken to hospital with bullet wounds and one of them later died.
Another eight received stab wounds or blows from iron bars.
According to local media, police arrested a dozen residents at the camp.
The families fell out over hooking up to the power supply, according to law enforcement officials.
They first came to blows, then pulled out knives and finally guns.
Toulouse’s right-wing mayor Jean-Luc Moudenc has called for the settlement to be cleared.
According to local media, police raided the same camp a year ago, arresting a dozen people and finding stolen train cables and copper.
The press were not allowed access to the crime scene on Friday and a police cordon of two kilometres was put in place.
Roma living in France face regular evictions from camps where they live in dire conditions, often without access to running water or electricity.