The Gare de Lyon train station in Paris has been evacuated after a fire in the area.
Police in the French capital urged people to avoid the area amid what was described as "unacceptable violence".
According to French media, the fire began on the sidelines of a concert by the Congolese singer Fally Ipupa.
Demonstrators have accused the musician of giving a voice to the Congo regime, AFP reports.
Officials had banned protests around the site of the concert arena - but dozens of protesters gathered in the area on Friday afternoon and evening.
Comportement scandaleux des manifestants qui empêchent les @PompiersParis d’accéder à l'incendie. https://t.co/zMYNv04Ykt
— Préfecture de Police (@prefpolice) February 28, 2020
Photos and videos from the scene showed fires and a thick cloud of black smoke rising.
Parisian police said 46 people have been arrested in connection with the demonstrations, while 54 others had been fined for taking part in a banned protest.
Police also said some protesters had engaged in "outrageous behaviour" by preventing firefighters from gaining access to the scene.
