:Routine maintenance on Facebook's network stitching together its data centers caused Monday's collapse of its global system for more than six hours, the company said on Tuesday.
At a U.S. Senate hearing on Tuesday, a former employee turned whistleblower accused Facebook of putting profits before people's safety, which the company denies. While users lost access to one of the world's most popular messaging apps - as WhatsApp has more than 2 billion users - employees were also blocked from internal tools.
The company said it sent a team of engineers to the location of its data centers to try to debug and restart the systems.