NEW YORK - Twitter experienced renewed outages Friday afternoon following hours of internet disruption that took down numerous sites earlier in the morning across the U.S. East Coast. 

A wave of reports of problems accessing many popular websites came after the servers at a major internet management firm were hit by a cyberattack.

New Hampshire-based Dyn said its server infrastructure suffered a distributed denial-of-service attack, which occurs when a system is overwhelmed by malicious electronic traffic.

In a statement provided to CBS News, the U.S. Department of Homeland Security said it was aware of the attack and is “investigating all potential causes.”

Dyn issued a series of statements about the service disruption early Friday local time, tweeting that as of 9:20 a.m. ET, “services have been restored to normal.” 

However, the company detected another wave of DNS attacks just before noon and acknowledged that the problem was not yet solved. “We are continuing to mitigate a DDoS against our Managed DNS network,” it said. 

The level of disruption caused was hard to gauge, but Dyn provides internet traffic optimization to some of the biggest names on the web, including Twitter, Netflix, Airbnb, Spotify, Visa and others, and users of many sites were reporting problems.

The site Downdetector.com, which tracks service outages, lit up with reports of problems accessing Twitter and other sites Friday morning.