Facebook and many apps in its suite of social media and chat services went dark for hours Monday in a widespread outage that appeared to affect users globally.

Facebook, Instagram, WhatsApp and Messenger were unreachable for many users, who instead saw a spinning wheel on their apps that never loaded.

Facebook’s internal communication platform, Workplace, went down altogether, said a person familiar with the matter who spoke on condition of anonymity because they weren’t authorized to speak publicly. As employees turned to third-party tools such as Slack, many found themselves locked out of even those, because Facebook’s mechanism for signing on to them was not working said another person familiar with the matter who spoke under the same conditions.

Facebook spokesman Andy Stone tweeted that the company was aware of the issues and was “working to get things back to normal as quickly as possible, and we apologize for any inconvenience.”

Reports on Downdetector suggest users across the United States, in Egypt, in Serbia and many other places were impacted. The issues began at about 11:39 a.m. Eastern time.

“Something happened internally at Facebook that messed with their network settings on how Facebook talks to the rest of the world and accesses the Internet,” said Courtney Nash, senior research analyst at security company Verica.

The issue seems to be with Facebook’s border gateway protocol routes, or paths that allow routers to exchange information, said Doug Madory, director of Internet analysis for Kentik, a network monitoring company. Madory calls them the “underpinnings of how the Internet operates.”

Facebook’s routes were withdrawn this morning, he said, and now Facebook’s apps cannot be found online because those routes contained the addresses of Facebook’s domain name system servers. DNS systems translate familiar Web addresses, such as facebook.com, into a string of numbers that computers can read. When the servers have issues communicating, it can make websites unreachable.

The outage appears to be global, Madory said, and it’s nearly unheard of to have such a large company go down for so long.

“This is massive,” Madory said. “It’s completely dead.”

It’s also possible the outage was affecting other Internet services, Nash said. When the services went down, so many users tried to load the sites that it caused a run on traffic on the Internet’s DNS infrastructure.

“The reason these failures are so crazy is because there’s so much interconnectiveness of the Internet we rely on,” Nash said.

The company hasn’t confirmed what caused the outage. Similar outages from other tech companies have been due to internal network configuration changes that caused errors, Madory said.

It’s unlikely Facebook was affected by an external hack, Nash said. If an internal change caused the issue, it could have been an update that mistakenly caused an error, or even an automated update, Nash said. It’s difficult to say without confirmation from Facebook.

"Was it malicious? I don’t know, I cant say,” she said.

As is typical when one social media site goes down, people flocked to another one to vent their issues. Twitter was full of Facebook and Instagram users checking in on other’s statuses.

“Oh no!” one user tweeted, with the hashtag #instagramdown.

Others were grateful for the break. “No worries, just leave it like that,” another user tweeted.

Twitter, the company, also got in on the chatter. “hello literally everyone,” its official account tweeted. But the fun didn’t last for everyone — Twitter’s support account tweeted in the afternoon that the extra traffic had caused some issues.

“Sometimes more people than usual use Twitter,” the post said. “We prepare for these moments, but today things didn’t go exactly as planned. Some of you may have had an issue seeing replies and DMs as a result. This has been fixed. Sorry about that!”

Some of Facebook’s leaders also turned to Twitter to share their own thoughts.

“*Sincere* apologies to everyone impacted by outages of Facebook powered services right now. We are experiencing networking issues and teams are working as fast as possible to debug and restore as fast as possible,” Facebook’s chief technical officer Mike Schroepfer posted.

On a lighter note, Instagram head Adam Mosseri tweeted that it “does feel like a snow day.”

The outage comes as Facebook faces increased scrutiny following a whistleblower — revealed this weekend as former product manager Frances Haugen — leaking tens of thousands of pages of documents, which she says shows the company has been negligent in eliminating violence and misinformation.

The WhatsApp outage was particularly hard for a huge swath of the world that relies on it heavily for messaging, especially in the around two dozen nations where the app is the messaging market leader.

According to the Global Web Index’s 2020 Social Media User Trends, seven countries — including Kenya, Malaysia, and Colombia — have over 90% of populations aged 16 to 64 as monthly WhatsApp users.

In the Middle East region, where both populations and governments rely heavily on Facebook and WhatsApp, the outage means a near-complete communications blackout.

Phone calls and text messages are expensive in countries such as Lebanon and Jordan, causing residents to turn to WhatsApp in particular. The app also offers encrypted voice calls, an important feature in a region rife with government surveillance.

In some countries, including Lebanon, political and public announcements are made almost exclusively via Facebook.

Several international newspapers from South Asia to South America were running news of the shutdown as the top story. El Tiempo, a news outlet in Colombia, quickly published a listing alternatives to WhatsApp, including Telegram. In the United Kingdom, digital news outlet The Independent is running a live update file on the social shutdown.

India has around 400 million WhatsApp users, and the service plays a heavy role during elections.

The World Health Organization capitalized on the moment to push forward more pandemic public health messaging.

Sammy Westfall, Sarah Dadouch, Will Oremus and Elizabeth Dwoskin contributed reporting.