I've also noticed that you can throw them underwater sometimes. However that doesn't always work.

In case you're the Squad leader:

Select every unit you want to cease firing with F1-F12 buttons and press 7. It should open a menu with commands like stealth, safe, danger and aware.
Select stealth and your squadmates will cease their fire and avoid engaging any targets they see. They will also seem to move more by crouching and sometimes go to prone.
If you want them to fire, just point them at the target and say open fire (which doesn't remove the stealth mode) OR just switch mode off by selecting danger, safe or aware.
All modes have different effects to A.I. I suggest that you try them out.