MONTREAL - Anti-tuition hike protesters started Friday with a bang as a group of 15 people vandalized the Montreal office of Education Minister Line Beauchamp.

Vandals broke a window, entered and trashed the office at around 8:30 a.m. before rejoining a group of 40 other demonstrators outside.

Police say seven people were arrested soon afterward.

Three people were arrested for participating in an illegal gathering, while another three were detained for mischief and participating in an illegal gathering.

The seventh person was arrested for break-and enter.

The arrests took place shortly after about 15 people smashed two windows and then vandalized Education Minister Line Beauchamp's office in her riding of Bourassa-Sauve.

The vandalism comes a day after provincial police announced the arrest of a man for allegedly threatening a Quebec cabinet minister.

They also said two other investigations are underway involving alleged threats against two ministers.

Police refused to name the ministers in question, but some media identified them as Beauchamp and Justice Minister Jean-Marc Fournier.

Meanwhile, a few dozen students at College de Valleyfield managed to get classes cancelled for the second straight day.

Administrators deemed it unwise to permit other students to cross picket lines set up by the demonstrators.

The provincial police monitored the situation, but there were no incidents.

On Wednesday, Education Minister Line Beauchamp instructed educational institutions to carry on as usual, regardless of demonstrations. The position angered protest leaders, some of whom redoubled their efforts to disrupt classes.

Montreal municipal authorities have floated the idea of banning masks at political protests, an initiative for which local police have long lobbied.

Real Menard, borough mayor for Mercier–Hochelaga-Maisonneuve, has also embraced a mask ban and spoke out in favour of such a bylaw Friday.