Really unfortunate to hear this extreme price movement, and I fear that because much of trading is automated these days that this may be a more than expected regular occurrence unless the proper controls are put into place.
I suggest researching other global exchanges and the solutions they have put forth, for example the CME’s rules put forth for “price limits” and “trading halts”. Price limits are the maximum % a price can move in a given period of time, and trading halts cause the book to stop allowing executions under given liquidity conditions.
These can be codified into your matching algorithm directly and should help avoid these extreme price movements, and ultimately can result in giving your customers a safer trading environment.
Hope this helps !