Sen. Mark Dayton (D-Minn.) said yesterday that he was closing his Capitol Hill office because of security concerns in what appeared to be an atypical response to intelligence information that has been shared with senators about terrorist threats.

Senate leadership aides said they knew of no other senator who plans to follow Dayton's example. Sergeant-at-Arms William H. Pickle scheduled a meeting today for senators' chiefs of staff to assure staffers that there are no new threats, according to the aides.

Sen. John W. Warner (R-Va.), chairman of the Armed Services Committee, issued a statement saying that he had also received briefings about security threats but saw no need to "take extraordinary steps such as those announced by Senator Dayton."

Dayton closed his office in the Russell Building across the street from the Capitol, and moved his staff to Minnesota and to office space off Capitol Hill. He said his Senate office will be closed while Congress is in recess until after the Nov. 2 elections.

"I do so out of extreme, but necessary, precaution to protect the lives and safety of my Senate staff and my Minnesota constituents, who might otherwise visit my office in the next few weeks," Dayton said in a statement announcing the closure.

Dayton said he could not disclose the contents of what he described as a "top-secret intelligence report" presented to senators by Majority Leader Bill Frist (R-Tenn.). But he added that he based his decision on a "careful review of all available documents" and decided to act on his own after Frist declined to convene a meeting of all senators to discuss the subject.

But several sources said other senators who attended briefings on the report did not come away with the same conclusion as Dayton did. U.S. intelligence officials have described the information as serious but vague, lacking specifics about the time or location of a possible attack.

The briefings were given on Capitol Hill by officials of the CIA and of a joint CIA-FBI agency that performs intelligence analysis, according to a government official who spoke on the condition of anonymity.

The briefers presented one particularly alarming scenario in which al Qaeda would launch multiple simultaneous attacks on the United States using weapons of mass destruction, and would overwhelm the U.S. government, the official said. This description was presented as a "worst-case scenario" -- just one in a range of possibilities, the rest of which were less worrisome, the official said.

"We're unaware of any credible threat information indicating al Qaeda is targeting a specific location in Washington or the United States," said Brian Roehrkasse, spokesman for the Department of Homeland Security. "Homeland Security has not made any recommendation for any member of Congress or other official in Washington to vacate their offices."

Staff writers Dana Priest and John Mintz contributed to this report.