A portion of Mayor Antonio Villaraigosa's office at City Hall in downtown Los Angeles was evacuated Thursday afternoon when a staff member opened letter that contained an unknown white powder.
Police and firefighters responded around 3:30 p.m. to the mayor's office on the third floor of City Hall and cordoned off the entryway.
Villaraigosa spokesman Peter Sanders said a letter was delivered to the office, and it turned out to contain a white powder.
Los Angeles Police Department spokesman Officer Chris No told NBC4 the substance was harmless chalk.
The employee who opened the letter apparently went to a nearby restroom, which was also blocked off by investigators. Fire crews were keeping the man inside the restroom while the investigation continued.
"We're not seeing any ill effects on this employee right now,'' Cmdr. Blake Chow of the LAPD Counter-Terrorism Unit said.
The fire department's hazardous materials crew examined the substance and it appears ``benign,'' he said, but the police department's own haz-mat team was conducting its own investigation.
Only the mail room was blocked off, he said, noting that the letter was addressed to the mayor.
"No one's taken a good look at letter yet,'' Chow said. "The letter and powder are contained in a room that's sealed off. If the substance is not hazardous, we'll start digging into the letter.''
Sanders said the mayor was in his office briefly during the situation, arriving just after the letter was opened.