Washington ( CNN ) -- The House of Representatives side of the U.S. Capitol is closed Thursday because of a construction-related incident , officials said . Police spokeswoman Kimberly Schneider said the incident is confined and not suspicious . A piece of ceiling fell down around 3 a.m. , exposing a chemical substance in a work area . Schneider did not know if the ceiling fell on a container , or whether the substance is liquid . Hazardous materials crews were on the scene . Laura Condeluci , spokeswoman for the Architect of the Capitol , said there was a `` potential release '' during `` asbestos abatement work '' on the House of Representatives side . `` Samples have been collected to determine whether there was potential exposure , '' Condeluci said .
The damage is minor and not suspicious , a police officer says . She says a section of ceiling fell around 2 a.m. , exposing a window in a work area . Hazardous materials crews are on the scene . Architect of the Capitol : There was a ` ` potential release '' during ` ` asbestos removal work ''