Brake system problem

I was driving my car BMW model 1992, 525i with a speed of 100 km/hr and suddinly applied a brake.the brake was not affective and I heared a brake banging of metal and I felt there was no brake after a while the ABS light came ON for a short of time.Then i Turned off the Ignition Switch and re-started the engine again the light went out and the brake was normal.Please advise me the probable cause.
thank you and best regards
Wiaam Al-Hassani