Parts of the U.S. Capitol were closed early on Thursday after an "industrial spill" occurred, although some tours of parts of the building were being allowed, according to U.S. Capitol Police.

A spokeswoman for the Architect of the Capitol said that during "ongoing asbestos abatement work there was a potential release" affecting the House of Representatives side of the Capitol.

Spokeswoman Laura Condeluci said samples were being collected to determine if there was potential harmful exposure in the incident, which began around 2:30 a.m.