Multiple House and Senate offices received suspicious letters containing white powder Friday, prompting the Capitol Police to deploy hazardous-materials teams to investigate. Field tests of the substances were all negative.

A final number of offices reporting such letters was not made available, but Officer Kimberly Bolinger, a Capitol Police spokeswoman, said that “numerous House and Senate offices” had received them and that the police have begun their investigation.

Bolinger said that all of the mail had been screened and irradiated before arriving at the offices, and that all of the offices had responded properly by immediately contacting the Capitol Police.

The offices of freshman GOP Sens. Norm Coleman (Minn.) and Saxby Chambliss (Ga.) were among those that received the letters, as was House Majority Leader Tom DeLay’s (R-Texas) personal office.

A Chambliss aide said that when the staffer who regularly handles mail opened the letter Friday morning, a white powder fell in his lap. The aide said the Capitol Police responded to their call immediately and that the office was not evacuated while the police conducted field tests.

“The Capitol Police were great,” said the aide.

The staffer added that the powder was folded up in an 8 1/2-by-11 piece of white typing paper with no writing or threats of any kind.

The letters had no return address on them, though sources said they bore the same Seattle postmark.

The Capitol Police sent out a voicemail message to every office Friday saying that “multiple” offices had received suspicious letters and emphasizing that all of the field tests were negative.

Some offices had false alarms. After the initial warning was put out Friday, Senate Minority Leader Thomas Daschle’s (D-S.D.) office found a seemingly suspicious letter that looked similar to the ones already found. The Capitol Police investigated and found that there was no powder in the letter.

The screening process that includes irradiation of the mail was implemented after a Daschle aide opened a letter containing anthrax in October 2001, prompting a massive shutdown on the Hill and a broad revision of Congressional security procedures.

Paul Kane contributed to this report.