New Mexico one of at least eight states to get letters. Denver Post reports letters are from Texas. The Governor's office has issued a press release with the details:

Governor's Office Evacuated Following Discovery of Unidentified Substance

The Governor's Office and the Lt. Governor's Office were evacuated today at 2:15 p.m. following the discovery of an unidentified, white substance that was delivered in an envelope.

State Police dispatched its Emergency Response Team to the State Capitol to investigate the substance. The U.S. Postmaster is also responding to the scene with specialized equipment to test the substance.

The Santa Fe Police Department, Santa Fe Fire Department and state Department of Homeland Security are also assisting the State Police with its investigation.

A portion of the Governor's Office was sealed off once the substance was discovered. Several staff members and security officers who were in the vicinity at the time the envelope was opened are currently being quarantined until the substance is identified.

Capitol Building Security evacuated the rest of the building as a precautionary measure, although the building is once again open except for the Fourth Floor, where the Governor’s Office is located.