The motivations behind today's massive denial-of-service attacks are still unknown, but the FBI and Department of Homeland Security are now looking into the incident.

As Politico reported earlier today, White House press secretary Josh Earnest told reporters that DHS was "monitoring this situation," as the agency said it was "investigating all potential causes." Reuters reports that the FBI is also investigating the attacks. The news service also reported earlier today that officials were investigating whether the incident was a "criminal act," although by now it seems clear the outages were almost certainly related to a targeted strike.

The DDoS, which first hit DNS service company Dyn, has affected several major websites, including Twitter, Spotify, The New York Times, and The Verge. Although Dyn, which is responsible for routing internet users to the proper website, said earlier in the day that it had the problem under control, another attack once again shut down several sites. An outage map appeared to show the outages intensifying throughout the day.