Police sources say there was an aggressive group of youths in the crowd, masked by bandanas and hoods. They started throwing stones, eggs and bottles at the police, and security forces had to use tear gas.

In Paris, Lyceum students and trade unions have been marching near the Bastille area, chanting the French song ‘It’s all for us’.

@LGThibaut Un jeune homme, assis mains dans le dos, interpellé par la police.

School Leonardo da Vinci, situated in the Paris suburb of Levallois-Perret, is on fire, witnesses report, posting pictures of black plumes of smoke on Twitter.

Protests are taking place all over France: in Marseille, Rouen, Rennes and other cities.

At the same time, in Rennes, protesters have been throwing projectiles and blocking railways, with smoke billowing in the city streets and police deployed all over the city.

@AnthonyDepe Paris #Loitravail: la violente charge policière piétine une manifestante #loielkhomri @OccupyFR #Manif5Avril

Having been chased from the railways by security forces, protesters are now marching towards the city center.

About 2,000 travelers are blocked on trains, a reporter for local media outlet 20minutes Rennes reported on Twitter. It is the third time railway traffic has been blocked in Rennes in the last three weeks, 20minutes reported.

New labor law reforms were proposed by Labor Minister Myriam El Khomri earlier in March. The French government is trying to battle high unemployment and has suggested cutting overtime pay for work over 35 hours a week.

According to the proposed reforms, employers would pay only 10 percent of overtime bonus, instead of the current 25 percent.

Previous protests were partially organized by a Facebook community called "Loi travail: non, merci" (Labor reform: No, thanks). Arguing that the reforms concern all French citizens, the group has started a petition that has so far been signed by over 1.2 million people.

According to an Odoxa survey for Le Parisien conducted Thursday, 71 percent of French people oppose the reform.