UPDATE:
We are able to login to some Microsoft services, looks like the issue is getting resolved, just because we can access some services, doesn’t mean others can too. It is still an ongoing issue.

It’s not just you. Many Microsoft services appears to be down for some users, preventing online sign-ins to Xbox One consoles and other services.

Microsoft took to Twitter to alert users of the problem.
We’re investigating an issue affecting sign-in for consumer services dependent on Microsoft Account authentication. Further information may be found via OL204479, OC204480, YC204481, SK204482, and WC204483 at https://t.co/k4X04c52ZD.
Twitter” @MSFT365Status

“There’s a temporary problem” message displayed on website pages.
Here is a response we got from Microsoft Support:
My sincere apologies for the inconvenience. We have received several reports about the Outlook account.
This has been a known issue, don’t worry, the Engineering team is already working on the fix. Our Engineering Team is still working on it and probably it will be fixed within 24 hours.

Microsoft states that the issue will be resolved within 24 Hours. If you’re already logged in – you will be fine but you’ll be unable to access many features until the issue has been fixed.
Let’s hope the issue will be resolved soon! For updates check @MSFT365Status on Twitter. Further updates will be here as well.
SOURCE: “Service Status” https://portal.office.com/servicestatus