Facebook, Instagram and WhatsApp are back. The apps, owned by Facebook, stopped working Monday for millions of users across the U.S., according to outage site Down Detector, writes ABCNEWS.

“To the huge community of people and businesses around the world who depend on us: we"re sorry. We"ve been working hard to restore access to our apps and services and are happy to report they are coming back online now. Thank you for bearing with us”, - Facebook said, once the apps began working again.

Later on Monday, the company explained why the outage occurred.

“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 said in a statement.

Despite the many theories that have been circling the internet since the outage, Facebook said it has no evidence that any user data was compromised during the disruption.

“Our services are now back online and we’re actively working to fully return them to regular operations. We want to make clear at this time we believe the root cause of this outage was a faulty configuration change. We also have no evidence that user data was compromised as a result of this downtime”, - they said.