An incident at Billown Dip during the third race of Wednesday evening led to the rest of Southern 100 programme being abandoned.
The club has issued a statement saying no-one involved has life threatening injuries and racing had to be stopped due to the state of the road and police carrying out a full investigation.
The start of racing was delayed earlier due to a diesel spill between the Stadium and Castletown Corner.
However, a shortened Senior Race provided a thrilling finish - Maurice Mawdsley:-
Guy Martin took the win just ahead of Michael Dunlop who once again set a new absolute lap record at 112.393mph.
The 650cc win went to Ryan Farquhar with William Dunlop coming out on top in the 250 class.
There's the final day of racing at Billown on Thursday with roads around the Billown Course closing at 9.50am. They will re-open at lunchtime, no later than 12.15pm, before closing again for the afternoon session at 1pm. Roads will then re-open no later than 5.30pm.