Video (00:49) : White powder in a letter opened at the governor's residence in St. Paul prompted hazardous materials personnel to respond.

A small amount of white powder found in a letter opened at the governor’s residence Monday prompted a team of fire officials to descend on the Summit Avenue residence in St. Paul.

Staff members of Gov. Mark Dayton detected the white powder when they processed the letter, and hazardous materials crews were called around 12:45 p.m. to the residence, authorities said.

Dayton was in the main residence at the time, but the letter was processed in a separate building.

The staff notified the State Patrol, which contacted the St. Paul Fire Department “out of an abundance of caution,” according to a statement from the state Department of Public Safety.

Two staff members were decontaminated as a safety measure but no one was taken to the hospital, said St. Paul Fire Deputy Chief Tom McDonough.

Fire personnel conducted two tests of the white powder but couldn’t definitively determine if it was hazardous or not, McDonough said.

St. Paul Fire Department crews responded to an incident at the governor's mansion Monday afternoon. It wasn't immediately clear why.

But preliminary tests by the Minnesota Department of Health found that the power wasn’t a biological threat, according to a statement issued late Monday by spokesman Doug Schultz.

“The substance is not one of the agents or pathogens we’re most concerned about, such as ricin or anthrax,” the statement said, adding that tests will continue for about 10 days to identify the power.

Lt. Eric Roeske, spokesman for the State Patrol, said the letter’s content was not threatening.

As of Monday afternoon, no arrests had been made in connection with the letter.

NICOLE NORFLEET

AND PAUL WALSH