The attacks against the social networking sites were denial of service attacks that were reportedly centered on a Georgian blogger who had accounts on both Twitter and Facebook reports Reuters. Twitter co-founder Biz Stone said Twitter would not speculate on the reasons for the attack.

Stone told Reuters, "Twitter has been working closely with other companies and services affected by what appears to be a single, massively coordinated attack."

The attacks left many Twitter and Facebook users unable to access the social networks and unable to post updates. Twitter was actually offline for several hours early in the day on Thursday. Facebook users were hit with login delays in addition to at times not being able to post updates.

Reuters reports that some speculate other sites, including Google were attacked as well. One social networking site called LiveJournal reports that it was attacked by the same group. Google reports that it had been in contact with some non-Google sites to help with the investigation. The search giant issued a statement saying, "Google systems prevented substantive impact to our services."

Steve Gibson from Gibson Research Corp told Reuters that the newfound popularity of Facebook makes it a target for this type of group. According to experts on cyber security, a single coordinated group could have been behind all of the attacks.

Kevin Price, CTO of Perimeter eSecurity said, "History would tell us that it's probably the same attacker or group of attackers that is launching both attacks."