My code is published as original work by a different group. What should I do?
This seems to be a clear case of plagiarism, and potentially a copyright violation.

The BSD license contains a line "Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer". If that was included in your Original code, then it seems that this was breached by the article authors.

But even in the case that this line was not included, then it seems to be still a case of plagiarism, as they are passing your work as theirs.

Contact the editor (or editorial office) of the journal. Provide them with a description of what happened (basically as you described in your question).
Also provide links to your originally online published source code. If you can, add proof of when you published it there (e.g. log files).

It would not hurt to also keep a copy of their present version of the source code they published, just in case it 'vanishes' from the internet and you want to show (e.g. to the editor/publisher) how they plagiarized you.