Facebook was hit with a denial-of-service attack on Thursday, on the same day Twitter was brought down.
But the attack did not appear to be as severe as one that crippled Twitter.
Facebook reported on its own Facebook profile that users may have had trouble accessing the site or its services because of the attack.
But the situation seemed well in hand by late morning in California, where the company is located.
"We have restored full access for most people," the company reported. "We’ll keep monitoring the situation to make sure you have the reliable experience you expect from us."
Users reported that Facebook was not loading properly or could not be accessed early Thursday, but the site seemed to be working properly by late morning.
Facebook did not provide specifics about the attack or how it was handled, only providing a link to a Wikipedia entry with information about DoS attacks in its posting.
It's unknown if the attacks on Twitter and Facebook are linked. However, a source with knowledge of the situation said that the company is working with Google and Twitter to investigate the matter further.
A portion of the service that redirects third-party-owned URLs to Google Sites or the Google Blogspot service also was affected for about an hour by a DoS attack this morning, another source familiar with the situation said.
It's also unknown at this time if that is related to the Facebook and Twitter attacks, the source said.
A DoS attack is an attempt to make a Web site or service unavailable to intended users by flooding the service or site with incoming data requests, such as e-mails.
Motives for DoS attacks vary, but perpetrators mostly target companies with high-profile, highly trafficked Web sites. Hackers often have a financial or political motivation for such attacks.