WASHINGTON — A massive congressional office building near the U.S. Capitol was briefly evacuated Thursday after concrete dust from a construction project entered the site.

The dust came from a rehabilitation project in the garage of the Rayburn House Office Building, Laura Condeluci, a spokesman for the Architect of the Capitol, told WTOP in an email.

Most of the building had reopened as of 9:30 a.m. Thursday except for an area on the southeast corner of the building that will remain closed until cleanup operations are completed, Condeluci said.

Rayburn, a 2.4-million-square-foot sprawling office complex for members of Congress and staff, is the largest congressional office building. It lies southwest of the Capitol between South Capitol Street and First Street.