Hordes of rampaging young Asian men chased a small group of men through the civic centre car park after they apparently came to protest against Harrow Central Mosque.
Hundreds of people had gathered in Station Road, united against any protest against the mosque, and determined to protect their religion.
When the small group of men arrived, chanting from the crowd turned to anger and groups of protesters, some armed with sticks, broke ranks and began to chase the men.
The men, who had arrived at Harrow and Wealdstone station to head down to the mosque, quickly turned and ran through the car park when faced by the hostile crowd, hotly pursued by the protesters.
Police tackled the protesters on the edge of the civic centre car park, stopping them catching up with the group of men, and a short stand-off ensued between officers and the marauding protesters.
They were eventually coaxed into returning to the mosque, as hundreds spilled into Station Road, forcing police to shut it down.