Facebook employees and an internal memo say that, several hours into the incident, Facebook's security experts were still trying to identify the root issue

Facebook employees and an internal memo say that, several hours into the incident, Facebook's security experts were still trying to identify the root issue  —  SAN FRANCISCO — Facebook and its family of apps, including Instagram and WhatsApp, went down at the same time on Monday.

The social network and the Facebook-owned platforms all stopped working around 11:30 a.m. ET Monday morning according to the site Downdetector.com. The outage affects nearly 7 billion users between the three platforms.  

Users going to Facebook's site saw an error page or an onscreen message that said, "Sorry, something went wrong. We’re working on it and we’ll get it fixed as soon as we can."

Instagram and WhatsApp are not showing new or updated content. On Instagram, messages including "Couldn't Refresh Feed" or  “5xx Server Error” appeared.

Facebook chief technology officer Mike Schroepfer issued an apology to users on Twitter: "*Sincere* apologies to everyone impacted by outages of Facebook powered services right now," he tweeted. "We are experiencing networking issues and teams are working as fast as possible to debug and restore as fast as possible."

The outage is having an effect on Facebook's moneymaker - ads. Facebook's U.S. digital advertising is estimated to be more than $48 billion annually, according to eMarketer.

Real-time online monitor Downdetector said it has seen more than 5.6 million reports about issues with Facebook and its services Instagram and WhatsApp since 11:15 a.m. ET Monday. Downdetector also said it received more than 123,000 reports of problems for Facebook, 97,000 for Instagram, 34,000 for WhatsApp and 9,600 for Facebook Messenger.

"Most users are reporting troubles with the website and apps overall," Downdetector said in an update. "This outage is still very much ongoing."

Earlier Monday about an hour into the outage, Facebook took to Twitter and tweeted: "We’re aware that some people are having trouble accessing our apps and products. We’re working to get things back to normal as quickly as possible, and we apologize for any inconvenience."

The outage comes after a whistleblower said that the world's largest social network is prioritizing profits over users' safety. 

Former Facebook product manager Frances Haugen said in an exclusive CBS’ “60 Minutes” interview Sunday that a 2018 change to the content flow in Facebook’s news feed contributed to more divisiveness and ill will in a network ostensibly created to bring people closer together.

Facebook's stock fell by nearly 5% on Monday. 

Social media meltdown. What happened?

How did all these networks get affected at the same time? Computer security writer Brian Krebs tweeted a possible answer for some of the problems: Facebook and Instagram were apparently removed from the DNS (Domain Name System) servers that basically make up the white pages of the internet.

When traffic is directed at Facebook's internet addresses, the addresses basically are not there because of the issue. "Visitors trying to reach a Facebook property, like facebook.com, will not get an answer and so the page won’t load," Muzaffar said.

"It is 100% an internet routing issue," said Andrew Wertkin, chief strategy offficer at BlueCat Networks. "The routes are missing from the internet. Why that happened we don’t know, nor the cause of it? The routes were withdrawn or yanked. We just don’t why they were yanked?"

Is Facebook.com for sale? Twitter reacts

As the incident continued, cybersecurity analyst Anis Haboubi tweeted what appears to be a "For Sale" ad for the Facebook.com domain.

Krebs saw it, too, and found domain name company GoDaddy also offering  Facebook.com for sale. "Bidding starts at....one beeleon dollars!" he tweeted.

Facebook.com was never seriously at risk of being sold, web domain company GoDaddy.com said in a statement to USA TODAY: "A third-party who doesn’t own Facebook.com attempted to list it for sale on Uniregistry.com and we inadvertently included it in search results. Because the third-party didn’t own or control the domain, it was never at risk of being sold and it remains with the current owner. The listing has been removed and is completely unrelated to any platform issues Facebook may be experiencing.”

Twitter had some reports of issues, but it was operational enough for the site – and CEO Jack Dorsey – to have some fun at Facebook's expense. With social media users all coming to Twitter, the site tweeted out, "hello literally everyone."

And Dorsey replied to the Facebook.com domain sale posting asking "how much?"

Even Instagram had to go to Twitter to tell its users that it was aware of, and working on, the problem.

"The DNS records that tell systems how to find Facebook.com or Instagram.com got withdrawn this morning from the global routing tables," Krebs tweeted. "We don't know why this change was made. It could well have been the result of an internal, system wide change or update that went awry. It's all speculation at this point why. FB alone is in control over its DNS records."

Facebook's service became unavailable – and remained unavailable Monday afternoon – and unreachable on the internet, according to web infrastructure company Cloudflare.

This occurred apparently because of an error in the Border Gateway Protocol (BGP), an internet traffic standard.  "From what we understand of the actual issue – it is a globalized BGP configuration issue," Usman Muzaffar, Cloudflare's senior vice president, engineering, told USA TODAY. "In our experience, these usually are mistakes, not attacks."