I have script including multiple commands. How can I group commands to run together. i.e.

#!/bin/bash command #1 command #2 command #3 command #4 command #5 command #6 command #7 command #8 command #9 command #10 

how can I run every 3 commands to gether? I tried:

#!/bin/bash { command #1 command #2 command #3 } & { command #4 command #5 command #6 } & { command #7 command #8 command #9 }& command #10 

But this didn't work properly ( the script is exiting with an error message)!