French police fired teargas and water cannons at thousands of firefighters protesting in central Paris on Tuesday over a lack of resources and professional recognition.
The demonstration started off noisily but peacefully, with whistles, smoke and sirens, before the situation got heated and firefighters scuffled with police as they attempted to block a main road.
The police resorted to firing teargas and water cannon at their fellow emergency services professionals.
Dozens more protesters assembled outside the parliament building, dispersing hours later after a stand-off with police.
Some brandished banners with slogans such as "Do more with less, welcome to the fire service", while others hit out at what they described as "political contempt" for their cause.
The interior ministry spoke of "isolated" incidents leading to six arrests and three police officers injured.
"Our numbers are falling, but we're overwhelmed by the number of call-outs. We're being asked to do everything, even replace ambulances. At some point, we just can't do it any more," Mathias Gosse, a 53-year-old firefighter from southwest France, told AFP.
Firefighters' trade unions are demanding higher premiums for fighting fires, to bring them in line with the equivalent bonuses for police.
The firefighters hailed the demonstration a success, putting the number of protesters at between 7,000 and 10,000. Paris police put it at 7,400.
Professional firefighters represent just 16 percent of a total 247,000 throughout France, the vast majority of whom are volunteers.
During their demonstration the firefighters received support from doctors, nurses and ambulance workers, who also denounced shortages in their own services.