Another bid was made overnight to occupy the Sorbonne in Paris, and there were also disturbances in several other cities as the protests over French labour law reforms continue.
Unions and student groups have distanced themselves from the violence, which police say involved a small minority of protestors.
Protest organisers have thrown down a Monday ultimatum to Prime Minister Dominique de Villepin; scrap the laws or widespread strike action will follow. The ultimatum came after a third day of national marches, in which organisers say over a million took part, although a much lower figure was given by the Interior Ministry..
Most of the marchers peacefully signalled their opposition to a package they believe will not boost youth jobs by making them easier to hire and fire. Some were less peaceful, and there were several arrests and injuries.
It is only the third time since the landmark student riots of 1968 that unions have joined the young in the streets. Their economic frustration appears to be shared by many.