Washington, October 22 (RHC)-- A U.S. company that manages crucial parts of the Internet’s infrastructure says it has come under a massive cyber attack, making major websites inaccessible to people across wide swaths of the United States.

Dyn, a company that acts as a switchboard for internet traffic, said it began experiencing a so-called distributed denial-of-service attack, or DDoS, early Friday morning, which extended throughout the rest of the day and into the evening.

A DDoS, occurs when hackers flood the servers with so much junk traffic that they freeze up. Such attacks are common, but there is evidence that they are becoming more sophisticated, more powerful and increasingly aimed at internet infrastructure providers.

Internet users reported about sporadic problems reaching several websites, including The New York Times, Netflix, Airbnb, Reddit, Etsy, SoundCloud, Spotify and Twitter. Reports that many sites were inaccessible started on the U.S. East Coast, but spread westward in three waves towards the evening.

The cyber attack appears to have relied on hundreds of thousands of Internet-connected devices like home routers, cameras and baby monitors that have been infected, without their owners’ knowledge, Dyn said.

Hackers used software that allows them to command the internet-connected devices to flood a target with overwhelming traffic. "The complexity of the attacks is what’s making it very challenging for us," said Dyn’s chief strategy officer, Kyle York.

The U.S. Department of Homeland Security and the Federal Bureau of Investigation (FBI) said they were investigating the incident and all potential causes, including criminal activity and a nation-state attack. Authorities said it was too early to determine who was behind Friday’s attacks.