MARSEILLE, France (AFP/REUTERS) - Hooded gunmen armed with Kalashnikov rifles fired on police in the French city of Marseille, just hours before Prime Minister Manuel Valls was to pay a visit on Monday, a police source said.

Elite police troops were sent to the scene, in the northern suburbs of the Mediterranean port city, after the shots, the source said by telephone. Police rushing to the scene were shot at when they arrived, added local public security director Pierre-Marie Bourniquel, who is running the operation.

Residents said the shots were fired "in the air", sources close to the case said, adding that there were no victims.

The La Castellane estate, where a 25-year-old was shot dead last month in a settling of scores, for years been plagued by rampant gang-related gun violence. Police say many murders in the city are linked to turf wars between multiple rival gangs battling for control of the drugs trade in the city's poorest neighbourhoods.

Caroline Pozmentier, deputy mayor of Marseille, suggested the incdient was part of a problem of drug trafficking in the area.

A school had been evacuated, she said, adding: "This battle against drug trafficking is a long-term battle."

Security forces are still hunting for those who fired the Kalashnikovs, and riot police will deploy in the estate over the next few days, Bourniquel said.

France has been on high alert for security incidents following the Islamist attacks in Paris last month that killed 17 people. Last week, two soldiers protecting a Jewish organization and radio station were wounded in a knife attack in the city of Nice.