The break-in took place in Aubagne, a town east of Marseille in the southern Bouches-du-Rhône region.
“At around 3.30am this morning, police in Aubagne discovered their station had been broken into,” Richard Derosas, a police spokesman, told BFM TV.
A number of weapons had been stolen from the station, causing police to suspect an attack at the nearby cash holding depot in Gémenos, scene of an earlier raid in January 2010.
Police raced to the scene where they found themselves confronted by the heavily-armed men. After a shoot-out between the two groups, the gang fled.
The attack had been well-prepared. After the break-in, the gang had left nails on the street in an attempt to slow down police vehicles.
Three burnt-out cars were later found. Police are still hunting the group.