Police evacuated 200 people from the Library of Congress' Jefferson Building yesterday after employes discovered a package containing explosives in a room being renovated.

The explosives, which police refused to identify, were found about 1 p.m.

A hazardous device unit of the U.S. Capitol Police removed the package from the building, placed it in an explosive-transport vehicle, and examined it at an undisclosed location, said U.S. Capitol Police spokesman Dan Nichols.

Those evacuated were kept outside the building, directly across from the Capitol at First Street and Independence Avenue SE, for about an hour, said Nancy Bush, a library spokeswoman.

Only about half of the people in the Jefferson Building, which houses the Main Reading Room and much of the library's valuable collections, were evacuated, she said.

All library tours temporarily were halted, and all visitors barred from the building.

Police returned to the Jefferson Building with bomb-sniffing dogs two hours after the discovery of the device when library security officers found another suspicious package, Nichols said.

Tours were again halted and dozens of library employes evacuated, but police said the second suspicious package proved to be a false alarm.

The explosives discovered at 1 p.m. did not appear to contain any timing mechanisms or written notes, Nichols said, and the library received no phone threats yesterday.

Police said they had no idea when the package was left in the room being renovated, or by whom.

Nichols would not identify where the explosives were found, and labeled what was discovered as "minor."

Bush said the explosives were not found near any of the tour routes in the 90-year-old building.

"This is an unusual occurrence," Nichols said. "We get a lot of suspicious packages, but it is very rare when they are determined to be explosives."

Bush said the library occasionally receives phone threats, but also called yesterday's incident "very rare."