VISTA, Calif. -- A North County traffic court annex on Melrose Drive was evacuated Tuesday when employees opened an envelope that contained a white powdery substance that turned out to be soap, authorities reported.

Just after 3 p.m., one of the two workers opened the envelope and found that it contained a second envelope, which held the talc-like material, Vista Fire Department Capt. Randy Pusey said.

"They felt they were exposed and called their supervisor, who called 911," the captain said.

The two traffic courtrooms and other areas were then evacuated.

The San Diego Fire-Rescue Department's hazardous-materials team and a crew from the county Health Department went to the scene to test the powder, the captain said.

About 5:15 p.m., the investigators gave an all-clear upon determining that the substance was a harmless cleaning material.