(CNN)Gunmen fired on police in a suburb of the southern French city of Marseille on Monday, the prosecutor's office said. Shots were directed at a police car, and police returned fire, according to prosecutors. There were no immediate reports of casualties. A SWAT team was sent to the scene. The gunfire erupted in Castellane, a suburb in northern Marseille that's known for its drug-related activity. France has been under a heightened state of alert since last month's terror attacks in Paris that killed 17 people. French Prime Minister Manuel Valls is scheduled to be in Marseille later Monday.
The gunfire was reported in a suburb of Marseille in southern France . Castellane is known for its drug-related activity .