Suspicious letters containing powdery substances addressed to governors were intercepted in least six states on Monday, but no injuries were immediately reported.

The letters were reported in Alabama, Michigan, Mississippi, Missouri, Montana and Rhode Island. They disrupted state governments in a few of the states, forcing some evacuations and testing for workers who might have been exposed.

Preliminary tests found the powders sent to Alabama, Mississippi, Montana and Rhode Island were not harmful. Results from Michigan were not yet available and the Missouri letter never made it to state offices.

Alabama officials said the FBI was working with police agencies in each state to investigate the letters. An FBI spokeswoman in Washington referred questions about the investigation to the bureau’s offices in each state.

Alabama’s public safety director, Christopher Murphy, said “my gut is there may be more” letters still moving through the mail system.

Mailroom workers in the basement of Alabama’s Capitol noticed the letter with an unidentified ingredient about 12:30 p.m. and notified police. Federal and state authorities closed off the street behind the building and set up a decontamination tent outside.

Murphy would not say where the letter originated or whether it contained any political message. The six governors addressed by the letters are split politically: four Republicans and two Democrats.

Another letter with an unknown white powder was opened by statehouse staffers in Rhode Island Gov. Don Carcieri’s Office of Constituent Affairs on Monday at about 3:45 p.m.

The business envelope was addressed to Carcieri and postmarked Dec. 4 from Dallas, Texas, but it was not marked with a return address.

No one was reported injured, but two employees who were exposed to the letter were initially quarantined and later allowed to leave the scene. Firefighters, state police and a hazardous materials team responded to the capitol to cordon off the scene and remove the letter.

In Jackson, Miss., Gov. Haley Barbour’s communications director, Buddy Bynum, said a letter arrived Monday with “some sort of powdery substance.” Staff who encountered the substance were also tested.

In Lansing, Mich., a package addressed to Gov. Jennifer Granholm was spotted about 2 p.m. at a state office building across the street from the Capitol. No injuries were reported and the powder was sent to be tested through the Michigan State Police.

The mailroom was evacuated and remained closed late Monday, but other offices in the building were not affected. Mailroom employees were evaluated and no injuries were reported, state Department of Management and Budget spokeswoman Kassie Kretzschmar said.

In Helena, Mont., authorities evacuated the state Capitol after finding a letter addressed to Gov. Brian Schweitzer. The building was evacuated and employees were sent home for the day.

In Jefferson City, Mo., Highway Patrol spokesman Capt. Tim Hull said a suspicious letter was found at an offsite state mail distribution center. It never reached the state Capitol, which remained open and operating normally with a student band and choir rehearsing for an annual Christmas concert in the rotunda.