Employees at San Antonio City Hall and the public were barred from the building for several hours after a suspicious powder was found in a newspaper delivered to the City Attorney's office Thursday morning.
Fire Chief Charles Hood did not say who the newspaper was meant for, but said that several copies are usually delivered to that office.
Hood said the powder, which has "about the same amount as a pack of sugar," was turned over to the FBI for analysis.
A fire department spokeswoman said the results were negative and there was no biological hazard.
As a precaution, an unknown number of city hall employees were told to "take a long lunch hour, but they weren't evacuated," Hood said.
Employees were allowed back into the building at 2 p.m.
No one was injured.