By CBSBoston.com Staff

BOSTON (CBS) — Facebook, Instagram and WhatsApp were all back online Tuesday after users were unable to access the sites for several hours Monday due to a major outage.

Facebook said they were aware of the outage at about 12:20 p.m. It was about six hours before the apps were up and running again.

Late Monday afternoon, Facebook’s Chief Technology Officer Mike Schroepfer said the problem was related to “networking issues.”

“Our engineering teams have learned that configuration changes on the backbone routers that coordinate network traffic between our data centers caused issues that interrupted this communication. This disruption to network traffic had a cascading effect on the way our data centers communicate, bringing our services to a halt,” Facebook VP of Infrastructure Santosh Janardhan said in a statement.

On Sunday night, 60 Minutes aired a story with a former Facebook employee who said the company routinely put money over safety, particularly when it came to hate speech and the dangers of Instagram to kids.

“A catalyst to this crash would be the whistleblower news that’s come out. That’s stirred up quite a bit of turbulence that’s come out around social media,” said cybersecurity expert Peter Tran.

A source told CBS News the problems were inside Facebook as well and company workers weren’t able to use their internal emails.

CBSBoston.com Staff