Some major Internet companies suffered service disruptions on Friday due to what Internet infrastructure provider Dyn said was a cyber attack that affected some sites, mainly for users on the East Coast of Canada and the U.S.

Some U.S. and Canadian Internet users had trouble accessing sites including microblogging site Twitter, music streaming service Spotify, discussion site Reddit and news site Vox, but others found the sites accessible in Europe or via mobile phones.

Amazon's web services unit said on its site that it had identified the root cause of the issue and was working to resolve it.

"Customers may experience failures indicating 'hostname unknown' or 'unknown host exception' when attempting to resolve the hostnames for AWS services and EC2 instances," Amazon said in the announcement on its site.

Dyn said what it described as an "attack" was mainly affecting the East Coast and that its engineers were working on it.

The outages happened as hackers launched a large distributed denial of service (DDoS) attack on Dyn's servers, tech news site Gizmodo reported.

An FBI representative said she had no immediate comment on the outages.

Dyn is a Manchester, New Hampshire-based provider of Internet infrastructure services, including managing DNS activity that connects a user to a website's servers.

Dyn's website says customers include some of the world's biggest corporations and Internet firms: Pfizer, Visa, Netflix and Twitter, SoundCloud and BT.

PayPal Holdings Inc also said that it has experienced some service disruptions due to the cyber attack on Dyn that caused Internet outages for its customers.

 "This has prevented some of our customers from being able to pay with PayPal in certain regions," said company spokeswoman Amanda Miller. "PayPal was not attacked directly, nor were any of our core services to business impacted in the disruption." 

A company representative could not immediately be reached to clarify Dyn's statement, made via Twitter, on the outages.