Shopify Outage Breaking Add to Cart, Checkout, Admin

We host a dozen or so Shopify stores, with wildly different daily volume.

One store averages ~$5k/hour and has kept usual pace while a different store that nets $1k/hour has had zero orders since 3pm.

It's possible this is affecting smaller stores?

Easily the worst outage of theirs I can remember and no ETA on resolution. Not sure if all stores are affected.