WASHINGTON (AP) — Thousands of Microsoft Outlook users reported issues with accessing and using the email platform Monday morning.

Microsoft 365 outage and problem reports peaked at almost 18,000 shortly after 11 a.m. Eastern Monday morning, according to outage tracker Downdetector. Reports have appeared to decline since then.

Most of the reports expressed issues with Outlook. Many users of Microsoft's emailing platform shared frustration on social media, with some noting they were unable to sign into or load their accounts.

The company said that it was “investigating an issue with accessing Outlook on the web” in a Twitter thread posted on its Microsoft 365 Status account — and later added that a “downstream impact” was also identified for Microsoft Teams, SharePoint Online and OneDrive for Business.

Shortly after noon ET, Microsoft 365 Status said it had “halted an ongoing deployment and are monitoring services to see if that provides relief to the environment.”

The Associated Press reached out to Microsoft for further statements Monday.