In sporting and military battles, when you are injured you are literally carried off the field. In the example it's not clear whether they were actually injured, or whether the speaker is worried that they might be.
Note that the grammar in your example is a kind of abbreviated style common to spoken military and police.
The following examples have the same meaning.
- Example: People find out X, there's going to be Y
- Fuller: If people find out X, there's going to be Y
- Fullest: If people find out X, then there's going to be Y