What were the big tank like vehicles that the police used to stop the protesters called?

From the text:

About four blocks ahead, slowly making its way up the street, was an enormous black vehicle—not a tank exactly, but it had six giant wheels, and its triangular metal nose looked designed to crash through concrete walls. One cop in all-black paramilitary gear stood in the lookout turret on top, and he surveyed the street as if he were looking for snipers.