Before the game started

[Bassim]

I am not sure if my sentence is correct. Would you please correct my mistakes?

Before the game started, there was a commotion in the stands the cause of which was unknown.

 

[emsr2d2]

Add a comma after "stands" and it's OK.

 

[Matthew Wai]

In case the OP does not understand why a comma is needed, see http://grammar-monster.com/glossary/non-restrictive_clauses.htm