Eleven hours after a cyberattack first hit the United States on Friday, the internet traffic company Dyn said the issue had been resolved. The disruptions began in the United States, then spread into parts of Western Europe, causing an internet outage that affected several popular websites, including the social network Twitter, money transfer services PayPal, music-streamer Spotify and the discussion site Reddit. Dyn, a New Hampshire company that manages crucial parts of the internet’s infrastructure, said it was under attack around 1100 UTC. WATCH: White House spokesman Josh Earnest on what they know Dyn, whose servers reroute internet traffic by hosting the Domain Name System (DNS), said it had resolved the first attack, only to face a second one around 1700 UTC. After fending off that second attack, Dyn said it was again experiencing problems in the evening. At the time, the company said it was investigating “several attacks.” Those were reported to be “resolved” around 2200 UTC. The U.S. Department of Homeland Security said it is investigating “all possible causes” of the outage. White House spokesman Josh Earnest called the attack malicious but said he had no information about who could be behind it. Internet users affected by the outage experienced sluggish surfing. The attack, called a distributed denial of service (DDOS) attack, occurs when hackers flood particular servers with internet traffic until they cannot handle the load and shut down. The attack also affected Airbnb, Netflix, Etsy, SoundCloud and The New York Times.