If you are employed on a job site and get injured on the job site, then you can file a workers' compensation claim and it would be covered by the employer. If there are additional safety concerns, such as the ones you have raised, you can file a complaint with Cal-OSHA about the working conditions.
Unsafe working conditions will likely to be the responsibility of your employer, not the building owner. However, in some situations there might be joint responsibility. This is an OSHA issue and you can report it anonymously through the website.
Good luck to you.
This answer should not be construed to create any attorney-client relationship. Such a relationship can be formed only through the mutual execution of an attorney-client agreement. The answer given is based on the extremely limited facts provided and the proper course of action might change significantly with the introduction of other facts. All who read this answer should not rely on the answer to govern their conduct. Please seek the advice of competent counsel after disclosing all facts to that attorney. This answer is intended for California residents only. The answering party is only licensed to practice in the State of California.
You should hire an attorney conversant in both worker's comp and personal injury law. It sounds like you may have a worker's comp claim, even though you never did say you got hurt. If you did, there may also be a 3rd party claim.
No information provided in response to these questions can be relied upon in any way without further personally consulting with Attorney Kerrigan and Attorney Kerrigan consulting personally with you regarding your specific legal situation.