A "glitter bomb" shut down the Rockville library Monday afternoon, after unsuspecting workers opened a letter and were showered with glitter and an unidentified powder.
Three employees were exposed to the letter, the glitter and the powder, Montgomery County fire officials said. They were called to the scene at about 12:30 p.m.
A hazmat team was called in, the three workers were quarantined and the library was evacuated while the contents of the letter were examined. No hazard was found, and the library was reopened at about 2 p.m.
Rockville City Police are investigating.