Some Apple stores couldn't make sales for hours this morning because of a tech glitch, and customers were furious

The outage that brought Apple's online store, iTunes, App Store, and other services offline for a couple hours this morning wasn't just a web problem.

A source tells us that it also brought some Apple Stores in Europe offline.

"All systems were down," our source said. "It was an epic f---up."

For about two hours this morning, employees couldn't check in to work, stores couldn't make sales, and Genius Bar appointments couldn't be kept. Employees couldn't check email until 3 pm London time.

There was virtually nothing that employees could do except talk to customers and answer phones.

Customers were furious and calling the stores to complain.

Employees are apparently worried because they were unable to register to get paid, but they're sure Apple will sort it out.

Apple blamed the outage on an internal DNS error. DNS is the system that directs Internet traffic to the correct places.

We reached out to Apple for comment and will update this story if we hear back.

There were also several reports of Apple Store problems in the US and UK on Twitter, and one person tweeted a picture of a store in Birmingham, UK, where employees were making sales using old-fashioned physical credit card readers: