Police thwarted an illegal night race in Warsaw. respective 100 officers and a helicopter

Drift after Warsaw, or night illegal races. They've been organized on capital streets for years. all time with the vulnerability of outsiders. On Saturday with the pump, the announced convention was thwarted by mass police operation. TVN24.pl reporters observed this action closely. Interestingly, the service has long known the group behind it. Then why can he inactive do it?