The Twitter account, @foxnewspolitics, one of many operated by Fox News, claimed that the president had been fatally shot while campaigning in Iowa, but gave no source for the news. On Monday morning, FoxNews.com first posted a brief statement saying that the reports were incorrect, and that it regretted “any distress the false Tweets may have created.”

The six messages were removed around noon on Monday, about 10 hours after being posted, but not before attracting a flurry of attention.

Because of the seriousness of the content, senior Secret Service officials held a conference call Monday morning to discuss the posts, said a law enforcement official who requested anonymity because of the investigation into the matter.

A spokesman for the Secret Service, George Ogilvie, said, “We are investigating the matter and will be conducting appropriate follow-up.” The White House declined to comment.

In a statement Monday afternoon, Twitter indicated that its own servers had not been broken into; instead, the e-mail account associated with the specific Twitter feed had been compromised, and from there the hacker or hackers had been able to gain access.

Twitter referred other questions about the incident to Fox News; a spokeswoman there did not immediately respond to a request for comment.

The FoxNews.com Twitter account for political news, which has about 36,000 followers, had been dormant since Friday, but at about 2 a.m. Monday, a message was posted there that eerily presaged the posts that would follow about the president: “just regained full access to our Twitter and email. Happy 4th.” The next post said that the president “has just passed. The President is dead. A sad 4th of July indeed.”

The next one said he had been “shot twice in the lower pelvic area and in the neck; shooter unknown,” and offered the disturbing detail that he “bled out.” The next post said that the president had been shot at Ross’s restaurant in Iowa.

The last message stated: “We wish @joebiden the best of luck as our new President of the United States. In such a time of madness, there’s light at the end of tunnel.”

Mr. Obama had been spending the weekend with his family at Camp David, and returned to the White House on Sunday, according to the official schedule.

FoxNews.com posted a short statement early Monday explaining what had happened: “Hackers sent out several malicious and false Tweets claiming that President Obama had been assassinated. Those reports are incorrect, of course, and the president is spending the July 4 holiday with his family. The hacking is being investigated, and FoxNews.com regrets any distress the false Tweets may have created.”

Twitter accounts are hacked from time to time, but Monday’s incident attracted national attention because an assassination had been mentioned and a major news organization had been affected. Increasingly, news organizations like Fox News have embraced Twitter as a means of promotion and interaction with readers.

The false Twitter posts about Mr. Obama seemed even more provocative because Fox News is widely perceived to be a voice of opposition to the Obama administration. On Monday, thousands of people on Twitter poked fun at the incident and at Fox News by pretending to guess Fox’s Twitter passwords.

A spokeswoman for Twitter, Carolyn Penner, would not address why the posts to the Fox News political account on Twitter stayed up so long, nor would she address reports about who was responsible.

A group calling itself the Script Kiddies claimed responsibility for hacking the Fox News Twitter account, according to Adam Peck, the outgoing editor of Think, an online student magazine operated at Stony Brook University on Long Island, who said he had communicated via instant message early Monday with a member of the group.

The Script Kiddies, Mr. Peck said, had posted to its own Twitter account that it hacked the political Twitter account of Fox News and wanted to speak to The Huffington Post, supplying an address at the instant-messaging service AIM. Mr. Peck, 23, said he figured he would try the address as well.

The first conversation took place around 12:38 a.m., Mr. Peck said, before the inflammatory posts to Twitter appeared. “We did ask them what their purpose was,” Mr. Peck said. “They said that they did align themselves with Anonymous and the antisec movement,” he added, meaning “antisecurity movement,” or hacking efforts intended to uncover information corporations or governments are trying to hide.

In the instant message, the person claiming to be a representative of the Script Kiddies said to Mr. Peck that there “will always be a group of people that need to stand up for everyone else and attempt to keep the governments in balance with its people.” The person claimed to be a former member of the better-known hacker group Anonymous.

According to the instant-message record, which Mr. Peck provided to The New York Times, the person with whom he communicated at Script Kiddies said that Fox News “was selected because we figured their security would be just as much of a joke as their reporting.”

Mr. Peck said he again contacted to the Script Kiddies when the first postings about the president were published, asking if the group had hacked the Twitter feed.

Mr. Peck said he received a message in response: “I cannot confirm that at this time. Stay tuned.”

Adding to the confusion, the Twitter account for the Script Kiddies at some point seemed to disappear, Mr. Peck said. He said he started “frantically searching elsewhere to find corroboration of this story.” But after 10 minutes of not finding it anywhere online, he said he figured it was the work of the Script Kiddies.

Several news reports have referred to Think’s interview, but for a time on Monday, the link to the interview was disabled. Mr. Peck, who will be graduating in December with a degree in journalism, said he suspected that the shutdown happened because of overuse.

“We’re not used to having all that much traffic,” he said.

Eric Schmitt contributed reporting.

This article has been revised to reflect the following correction:

Correction: July 4, 2011

An earlier version of this article erroneously defined the “antisec movement” as meaning “anti-secrecy.” In fact it means “anti-security.”

Article source: http://feeds.nytimes.com/click.phdo?i=d319c69858de3864fe1d305be8601283