Internet users worldwide received a jarring reminder today about just how reliant they are on Google, when the Silicon Valley giant suffered a major outage for about an hour, sending many of its most popular services offline.

At a time when more people than ever are working from home because of the pandemic, Google services including Calendar, Gmail, Hangouts, Maps, Meet and YouTube all crashed, halting productivity and sending angry users to Twitter to vent about the loss of services. Students struggled to sign into virtual classrooms.

Google disclosed the outages on a status dashboard that shares information about its various services. Downdetector, a website for tracking internet outages, also showed that Google was offline. Google’s search engine continued to work for some people.

But about an hour after the outages began, the services started working again.

It was not immediately clear how many users were affected by the outage. Several of Google’s products have more than 1 billion global users, including Android, Chrome, Gmail, Google Drive, Google Maps, Google Play, Search and YouTube.

In a tweet, the company attributed the problem to an “authentication system outage” that lasted for approximately 45 minutes starting at 2:32 a.m. Hawaii time.

“We apologize for the inconvenience and thank you for your patience and continued support,” Google said on its website. “Please rest assured that system reliability is a top priority at Google, and we are making continuous improvements to make our systems better.”

A Google spokesperson had no further comment.

Product outages were once fairly common for growing internet companies. But as Google, Facebook and others have become larger, building complex networks of interconnected data centers around the world, the incidents have become less common. Google has privately financed undersea cables to move data between continents and improve performance in the event problems occur in a certain location.

The reliability of the systems have become increasingly important as people and businesses depend on the services, whether to search for information online, find directions, send email or get access to private documents stored on Google’s servers.

During lockdowns, schools have leaned on Google services to teach students forced to stay home.

“At least we have an excuse for not doing our homework,” one person wrote on Twitter.