LONDON — Residents swept up broken bricks, shattered glass and burnt plastic on Wednesday after far-right protesters clashed with police outside a mosque in a northwest England town where three girls were fatally stabbed.

A violent crowd of several hundred hurled bricks and bottles at riot police and set garbage bins and vehicles on fire in Southport, hours after a peaceful vigil for the girls, aged 6, 7 and 9, who were killed during a Taylor Swift-themed summer holiday dance and yoga class. The ambulance service said it treated 39 police officers for injuries, 27 of whom were taken to hospital.