this is in ontario london, so we are a group of 5 people each renting a room in the house and we are all working, landlord came in the morning while most of us were out and he started moving our stuff out of the basement common area and made a new room out of thin air

https://freeimage.host/i/Lh63og

he came to show him the room 2 days ago without notice, came today without notice, moved our stuff , and now we have a new tenant out of this air

Is this legal? what can we do?