A critical security vulnerability was recently patched within the Linux kernel called:
CVE-2017-1000364
https://rhn.redhat.com/errata/RHSA-2017-1486.html
We have already applied this update to our servers, but this kernel update required the servers to be rebooted in order to enter the secured kernel. This was completed just a few minutes ago and we are back online with less than 3 minutes downtime.
Please note that this is a critical vulnerability with the CentOS Operating System and doing nothing would have been blatantly insecure, as the server would be vulnerable to root compromise.