At about 40 seconds into this video, the reporter says (as I can discern it) "Several of the women stood at their ground and were stabbed as they chanted slogans..." My impression is the "stood at their ground" part means that women did not retreat when aggressors wanted to suppress them. Nevertheless, the presenter's accent is British and I am not sure what he means.
There is no preposition at in the sentence.
Several of the women who stood their ground with considerable courage were stabbed as they chanted slogans for equal rights.
To stand one's ground is an idiom:
to refuse to be pushed backwards, or to continue in your beliefs in an argument.
[Cambridge Dictionaries Online]