A 30-year-old Iraqi migrant received a gunshot wound in the groin area and a 25-year-old man whose nationality was unknown was wounded in the side in the incident in the Grande-Synthe camp Monday, a police source said.
Both men required hospital treatment but neither had life-threatening injuries.
"A police investigation is under way to establish the precise circumstances of this row and who fired the gun," a spokesman for the local authorities said, AFP reported.
The shooting followed an incident in which two migrants suffered minor knife wounds in the camp on Sunday.
The Grande-Synthe camp was built by the Medecins sans Frontieres (Doctors Without Borders) charity and the local authorities in accordance with international humanitarian norms and currently holds nearly 800 people.
Charities and migrants' associations say pressure is building at the nearby "Jungle" camp in Calais, after what they say is an influx into the camp in the summer months.
Some groups believe 9,000 people are now crammed into the Jungle, which is a largely makeshift camp although 1,750 residents are housed in more permanent accommodation created from shipping containers.
Local authorities are due to carry out a new head count this month but for now are sticking to the figure of around 4,500 from a survey in mid-June.
French authorities have made repeated efforts to shut down the Jungle.
Thousands of migrants and refugees gather in Calais and other ports on France's northern coast, hoping to smuggle themselves aboard lorries that are crossing the Channel to Britain either through the Eurotunnel or on board ferries.