Supply chain package poison

Your GitHub org alerts that a third-party CI app's OAuth token was used to clone 30 private repos from IPs in two countries overnight, and one repo's main branch got a force-push adding an obfuscated post-install script to a published npm package. The third-party CI vendor disclosed a breach of their token store yesterday. Several of your customers consume that npm package. The malicious version was published to the registry 6 hours ago and has ~200 downloads. How do you triage, contain, and remediate this supply-chain account-takeover?