Baltimore County police and fire units responded Tuesday morning after a suspicious powder was found at a processing center for the U.S. Census Bureau in Essex. The powder was found to be harmless, a Fire Department spokeswoman said.

Police and fire departments were called about 10 a.m. to the Census Bureau's Data Capture Center, in the 8400 block of Kelso Drive, to examine a package containing a small amount of powder.

"We did not evacuate the building, no one was showing symptoms, there were no transports," said Fire Department spokeswoman Elise Armacost. "People were removed from the immediate vicinity while we were testing."

The plant, which processes census questionnaires as they are returned, resumed operations by early afternoon, said Markia McLeod, a spokeswoman for the Census Bureau.

McLeod said hazardous-materials teams have been called to the Essex facility six times since it opened last year. Prior to Tuesday's call, the most recent incident was in March, when powder found inside a census envelope turned out to be coffee creamer.