If someone is dying in front of you by law are you obligated to seek help for them?

Not unless you have a duty to that person established by unique relationship or circumstance. A parent would be obligated to save a child where he could do so without risk to himself. The "duty to rescue" is almost universally NOT formalized in law. It exists purely as a moral obligation in most situations.

You have (in most places) a "duty of care" that includes seeking help for injured or providing first aid if such aid is not available.

In some places you can get fined for not helping.

In others you can be sued.