The gold standard in disaster PR response is the Tylenol crisis of 1982. Somehow poison was ending up in some Tylenol capsules and a little girl had died.
Before even fully knowing what was going on the company apologized, issued a nationwide recall, and replaced product ads with announcements warning people not to consume their product.
When an internal investigation revealed it was someone tampering with products after they were on shelves and resealing them, the company announced it would relaunch the product with an innovative tamper-evident cap and offered a reward for information leading to the culprit.