Is it grammatically correct to say that "two groups of people stared at each other" since, by itself, a group can't do anything? It's the people within the groups that do the staring, not the groups themselves, but I don't know how else I would go about wording this. If you have any suggestions for a substitute sentence that means basically the same thing, feel free to state it.
Also, if this question is in the wrong category/under the wrong tags, please let me know! I'm new to this site so I don't quite know how everything works yet.