The hacker group Anonymous has taken credit for shutting down the city of Columbia website, said Tony St. Romaine, deputy city manager. But St. Romaine acknowledged he can�t be sure the group is behind the attack.

Its motivation is the Feb. 11, 2010, Columbia Special Weapons and Tactics raid of Jonathan Whitworth�s home, St. Romaine said. The SWAT team found a misdemeanor amount of marijuana and shot two dogs in the home, killing one. Release of a video of the incident in May 2010 sparked outrage and spurred changes in police policies and procedures governing such raids.

After KOMU television reported the Anonymous connection, the station also suffered a DDOS attack that shut down its website, said Josh Kranzberg, executive producer. He said that was around 2:30 p.m. Friday. A message on KOMU�s Twitter feed said the website was to be down for 24 hours, but it was back up shortly after the tweet. Kranzberg said the information technology staff found a solution. He said he is not aware of anyone taking responsibility for the attack.

�I hope it doesn�t happen again,� Kranzberg said.

Anonymous is a loosely organized network of activist hackers. The group is known for sporting Guy Fawkes masks.

St. Romaine said city information technologies staff members were alerted around 11 p.m. Wednesday to what is known as a distributed denial of service, or DDOS, attack on the city website at gocolumbiamo.com. He said network security issued an alert that the site was under attack.

The attack flooded the website server with requests from multiple sources. The website remained offline Friday afternoon.

St. Romaine said until staff can find a way to filter out the malicious requests, all access to the website has been blocked. He said these types of attacks don�t result in the theft of information.

�We�re 100 percent sure this is a distributed denial of services attack,� St. Romaine said. No damage to the city�s systems is expected, because it�s designed to shut the website down, not to remove or destroy data.

�We�re very certain that�s not the case,� he said of information theft.

St. Romaine said the city�s network security protects it from hacks and viruses and other malicious attacks, but there is no real protection from a DDOS attack.

�Any sort of network systems are all very vulnerable to this type of issue,� he said.

St. Romaine said he found the information about Anonymous being behind the attack on the Counter Current News website. The Anonymous Press Twitter feed also links to the site.

�Anonymous hacktivists have targeted websites for the city of Columbia, Missouri after a video was brought to their attention, clearly documenting a SWAT team raid where two dogs were shot without provocation,� the item at Counter Current News began.

The site contains a link to a Youtube video of the incident, with an introduction by someone who calls himself Bitcoin Baron. Bitcoin Baron in the video�s comments section denies he is part of Anonymous and is upset that Anonymous is getting credit for his work. The Youtube site links to a Twitter feed with the name Jack Hammer.

Anonymous, Counter Current News and Jack Hammer didn�t immediately respond to questions sent via Twitter and email.

St. Romaine said he can�t be certain Anonymous is behind the attack.

�These perpetrators, they do a very good job of hiding their tracks,� St. Romaine said. He said there are some situations where innocent computer users could be part of an attack without knowing it.

St. Romaine said city officials have been in touch with the FBI about the incident.

�Violations like this are a federal crime,� St. Romaine said. �This group, they have done this on numerous occasions, and it�s hard to identify individuals.�

Joel Sealer, a spokesman for the FBI in Kansas City, said only that city officials had been in contact with the agency, but he would not comment on any investigation or confirm there is an investigation.

St. Romaine said he did not know when the city website would be back online.

�We�ll just have to wait it out and see what happened and see if we need to take more extreme measures,� he said.