The West Coast is now under web attack. A host of websites are unavailable, including Twitter, in what appears to be a second assault Friday against a firm that connects internet users to websites.

The U.S. Department of Homeland Security is reportedly investigating. The attack raised fears that this could be a trial run for an attempt at a major disruption of the U.S. presidential election.

“Say, not to panic anybody, but what if the (attacks) today were practice for 11/8 ?” high-profile pundit Keith Olbermann tweeted.

While many of the websites affected by the first attack, which hit the East Coast, are back up, sites hosted on the West Coast, including Twitter and Recode, have been hit, and were unavailable for many as of 11 a.m. Friday.

As of 11 a.m., Dyn’s online update about its response to the attacks said the company was continuing to “investigate and mitigate.”

The outages appear to have resulted from a “distributed denial of services” attack on web hosting firm Dyn. Firms such as Dyn “act as the internet’s phone book and facilitate your request to go to a certain webpage and make sure you are taken to the right place. If the (domain name server) provider that handles requests for Twitter is down, well, good luck getting to Twitter,” explains Gizmodo.

“Distributed denial of service” attacks bombard an online service with so many messages from so many sources that the service is overwhelmed and can’t function properly. Commonly, attackers gain access to unsecured “internet of things” devices such as printers and security cameras, hijack the devices and direct messages from them to the target.